WHAT HAPPENED AT MIDNIGHT

FRANK and Joe Hardy receive an unusual assignment from their detective father. They are to âbreak intoâ the house of a Bayport neighbor, Malcolm Wright, and retrieve a top-secret invention that the scientist had hidden in his study before leaving for California. The invention is in danger of being stolen, and the boys race against time to beat the thieves at their own game.

But the young detectives soon discover that they are involved in a mystery far greater in scope than just retrieving the invention. Their investigations put them on the trail of a dangerous gang of jewel thieves and smugglers. When Joe is kidnapped, this incident starts Frank off on a chase that almost ends disastrously for him and his pals.

The exciting capture of several members of the gang during a stormy night on Barmet Bay and a perilous encounter with the insidious Anchor Pete concludes one of the most complicated cases of the Hardysâ career.

The subway train rapidly gained on them!

Copyright Â© 1995, 1967, 1959, 1931 by Simon & Schuster, Inc. All rights reserved.

Published by Grosset & Dunlap, Inc., a member of The Putnam &
Grosset Group, New York. Published simultaneously in Canada. S.A.
THE HARDY BOYSÂ® is a registered trademark of Simon & Schuster, Inc.
GROSSET & DUNLAP is a trademark of Grosset & Dunlap, Inc.

eISBN : 978-1-101-07625-5

2008 Printing

http://us.penguingroup.com

CHAPTER I

Burglars

âWHAT an assignment! And from our own Dad!â

Joe Hardy grinned at his brother Frank as the two boys slipped into ripple soled shoes and put on dark jackets.

âFirst time weâve ever been asked to play burglar,â Frank answered with a chuckle.

A few days before, their father, an ace detective, and Malcolm Wright, an inventor, had left for California to hunt for Wrightâs valuable stolen antique plane. Because they would be delayed in returning, the inventor had requested the brothers to âbreak intoâ his home and retrieve a top-secret invention before thieves took it.

âA little second-story work around midnight,â Joe mused, âand all because Mr. Wright left his keys inside the house and locked everything but that one bedroom window with a broken lock.â

âThe invention must be something super or Dad and Mr. Wright wouldnât have asked us to guard it with our lives,â Frank remarked. âI wonder what it is.â

âDad gave us permission to find out. Say, suppose we canât locate that secret compartment we think is in Mr. Wrightâs desk before those thieves arrive?â Joe asked. âI wish Dad could have given us all the details before the call was cut off and we couldnât get it back.â

Joe, who had blond hair, was a year younger than his dark-haired, eighteen-year-old brother Frank. Both had solved many mysteries, some of them for their father.

Fenton Hardy had told the boys on the telephone that just before Mr. Wright had left Bayport, where they all lived, he had been threatened by a mysterious gang. They had learned about the invention from a worker in a factory that had made some of the parts. He had breached the confidence placed in him.

The caller had told Mr. Wright that if he did not voluntarily turn over his invention before a certain time, âvisitorsâ would come for it. The date they had set was the following day!

âMr. Wright didnât have time to put the invention in a safe-deposit box, so he hid it in his study,â Fenton Hardy had said. âHeâs afraid the thieves may break into his house, so he has alerted the police to be there tomorrow morning. But heâs worried and he wants you boys to get the small box containing the invention before then. Donât leave it at our house when youâre not there. Keep it with you at all times but well hidden.â

Frank and Joe relayed the conversation to their pretty, understanding mother, and to Aunt Gertrude, their fatherâs maiden sister who lived with them. She was inclined to be critical of her nephews involvement in detective work.

Instantly she said, âBe burglars! The idea! Why, suppose you fall off that houseâIâ

âGertrude, please!â Mrs. Hardy broke in. âDonât even mention such a possibility. I know the boys will be careful.â

âOf course,â said Joe. âLetâs go, Frank!â

The brothers hurried to the garage where their shiny convertible gleamed in the light of a street lamp on the corner of High and Elm streets. Frank took the wheel and drove to within a block of Mr. Wrightâs rambling, old-fashioned house. The boys walked to it and were glad to see that the building stood in deep shadows.

They reconnoitered the grounds in silence. No one was around. Finally Frank whispered, âI guess our best bet to the second floor is that trellis. It looks sturdy. Weâll go across the roof over the kitchen door and edge around to the unlocked window.â

âIâll stay close by and hold onto your legs until you make it,â Joe answered.

They followed each other up the trellis and crossed the narrow roof. Fortunately there was not much pitch to it. Joe crouched and grasped his brotherâs right leg.

âAll set,â he announced in a whisper.

Frank stretched over to the window ledge but could not reach the top of the sash to raise it.

âGive me a push upward,â he murmured to Joe, who hoisted his brother until his fingers reached the top of the sash.

The window lifted easily. Frank pulled himself sideways through it. âYour turn, Joe.â He reached out and grasped his brotherâs outstretched hands.

Joe, a little shorter than Frank, found he could not reach the window without swinging precariously in space. If Frank couldnât hold his brotherâs weight, he would be dragged outside. Both boys would plunge to the ground!

âNo use being silly about this,â Frank said. âIâll open the rear door for you.â

Joe was about to climb down the trellis when a strong light suddenly lit the area.

âA car!â Frank exclaimed as the driver beamed a searchlight on their side of the street. âMaybe the thieves are in it! Duck!â

Frank quickly closed the window, while Joe flattened himself face down on the roof. He did not stand up until the area was in darkness again. Then he hurried down the trellis and through the rear door.

âDuck!â Frank exclaimed. âMaybe the thieves
are in that car!â

âClose call!â said Frank.

Joe nodded. âI thought maybe it was a police car, but I guess not. It had no revolving top light.â

His brother agreed. âIâm sure Mr. Wrightâs enemies are casing this place!â

âYes. And theyâll probably be back soon! Weâd better get moving.â

Holding their flashlights low to the floor, the boys sped up the stairs and found Mr. Wrightâs study. A large walnut desk stood in the center of the room. Frank and Joe walked to the front of it, where there were drawers to left and right of the wide kneehole.

âThe secret compartment may be in one of them,â Joe suggested.

âTheyâre not locked,â Frank whispered in amazement.

The boys searched diligently, lifting aside letters and other papers. They found nothing.

âNow what?â Joe asked.

Frank had an idea. âIâll look in the kneehole while you hunt for movable panels on the outside of the desk.â

Again there was silence as the two boys began to finger the woodwork. Minutes went by, then Joe said, âIâve found something that moves.â

Frank crawled out and watched as his brother slid open a panel, revealing a long, narrow space.

âAnything in it?â Frank asked.

Joe beamed his flashlight inside. A look of disappointment came over his face.

âNothing,â he announced. âThere might have been at some time, though.â

âYou mean the invention?â

âMaybe. How are you making out?â

âSomething in the kneehole looks suspicious,â Frank answered.

Just then the boys heard the crash of glass and immediately clicked off their flashlights. Someone had broken a windowpane, and at this moment was no doubt reaching inside for the lock. Any minute one or more men might mount the stairs and enter the study!

The boys looked for a hiding place. There were no draperies, sofa, or large chairs, and no closet.

âLetâs hide in the kneehole,â Frank whispered, âthen use our hand signals.â

Some time before this, the Hardys had devised a series of hand-squeeze signals. One hard squeeze meant, âLetâs attack!â Two indicated caution. Long, short, long meant, âWeâd better scram.â An ordinary handshake was, âAgreed.â

âIf there arenât more than two men, letâs attack,â Joe said in a barely audible tone.

âOkay.â

Quickly the two crawled into the kneehole and pulled the desk chair into place. The boys were well hidden when they heard footsteps on the stairs, then voices.

âNo failing this time or Shortyâll take us on our last ride,â said a man with a nasal voice.

Frank and Joe wondered if the men had tried to break in earlier but failed.

The manâs companion spoke in lower tones of disgust. âOh, youâd believe Shorty invented fire if he told you he did. He ainât so great. Takes orders from the boss, donât he?â The other did not reply.

The two men entered the room and beamed flashlights around. âWhere did Wright say he kept the invention?â the deep-toned man asked.

âI got in late on the conversation when I tapped that telephone call to the Hardy house,â the other answered. âBut I did hear the words âsecret compartment.â Where would that be? The desk?â

Frank and Joe froze. Were they about to be discovered?

âNo, not the desk,â the other man said. âThe safe.â

For the first time the boys noticed a small safe standing against the wall opposite them. Frank and Joe were fearful the men would detect their hiding place, but the attention of the burglars was focused on the safe. In a moment they squatted and the boys got a good glimpse of their faces. Both were swarthy and hard-looking.

At that moment the tower clock of the town hall began to strike. It was midnight!

The men waited until the echo of the twelfth stroke had died away, then the one with the nasal twang put his ear to the dial of the safe and began to turn the knob.

After a few moments his companion asked impatiently, âWhatâs the matter? That safecrackinâ ear of yours turned to tin?â

âTumblers are noiseless,â the other said. âGuess weâll have to blow it.â He began to take some wire from his pocket.

Frank and Joe were trapped. If the door of the safe were blown off, it might head right in their direction!

Quickly Joe felt for Frankâs hand and gave it a hard squeeze, meaning, âLetâs attack!â

Instantly Frank answered with the âAgreed!â handshake.

In a flash Joe flung the desk chair at the two men, then the boys jumped them!

CHAPTER II

Amazing Invention

TAKEN by surprise the burglars were at a disadvantage. Frank and Joe knocked them to the floor and sat on their backs.

âUgh! Whatâs goingâ?â one mumbled.

The men were strong and with great heaves they tried to shake off the boys. Frank and Joe pressed down hard.

âWho are you?â Frank demanded.

No answer. Then suddenly the man Joe was holding rolled over and tried to sit up. Joe kept him down and the two, locked in a viselike grip, twisted to and fro across the floor.

Frank, meanwhile, had found his deep-voiced opponent a kicker, who viciously jabbed his heels into the boyâs back. Angry, Frank sent two swift blows which grazed the manâs chin.

The other two fighters bumped into them. In the mix-up the burglars were able to throw off their attackers and scramble to their feet. The four began to exchange punches.

âFinish off these guys!â the nasal-voiced man rasped.

For several seconds it looked as if they would. Their blows were swift and well-aimed. Then both men, breathing heavily, relaxed their guard. In a flash Frank and Joe delivered stinging upper-cuts to their opponentsâ jaws. The burglars fell to the floor with thuds that shook the house. They lay quiet.

The boys grinned at each other and Joe said, âKnockouts!â

Frank nodded. âWe must notify the police to get out here before these men come to.â

âWe can wait,â Joe answered. âTheyâll sleep for at least half an hour. Letâs find that invention first!â

âGood idea.â

Though bruised and weary the boys eagerly searched the side of the kneehole where Frank thought he had found a clue. There was a slight bulge in the wood. After pressing it in several directions, a panel began to slide counterclockwise. There was a click.

Just then one of the burglars groaned. The Hardys tensed. Was the man coming to? Joe leaned forward and beamed his flashlight on the two figures. Both were still unconscious.

Meanwhile, Frank had lifted out the panel. The space behind it contained a small metal box. Written on the box was: Property of Malcolm Wright. Valuable. Reward for return.

âIâve found it!â Frank exclaimed.

âThen letâs go!â Joe urged.

âOkay,â Frank agreed. âYouâll find a phone in the lower hall. Call the police while I slip this panel back. Take the box.â

In a minute Joe was dialing headquarters. Without giving his name, he said, âCome to Malcolm Wrightâs house at once. There are burglars in it.â He hung up.

Frank joined him and the boys dashed out the rear door. They took a circuitous route to their convertible to avoid being questioned by the police. At a cross street they saw a police car apparently speeding to the inventorâs house.

âWhere do you suppose the burglarsâ car is?â Joe asked. âYouâd think theyâd have a lookout.â

âMaybe itâs cruising,â Frank suggested.

The boys hopped into their convertible. As an extra precaution against a holdup and possible loss of Mr. Wrightâs invention, they locked themselves in.

âBoy, a lot can happen in an hour,â Joe said, looking at the car clock. He reached over and turned on their two-way radio to police headquarters. âI wonder if thereâs any news yet from the Wright house.â

The boys were just in time to pick up a broadcast. An officer was saying, âSend the ambulance to Wrightâs house.â

âAmbulance?â Frank echoed. âJoe, we didnât hitâem that hardâor did we?â

The policeman went on, âThese guys arenât bad off, but they sure got knocked out. Looks like a gang feud. The men who kayoed them may have done the stealing.â

Frank and Joe chuckled. âSomeday weâll tell Chief Collig,â Frank said, âbut right nowââ

He stopped speaking as a loud crack of static burst from the radio and a vivid flash of lightning made the night turn to day momentarily. A long roll of thunder followed.

âLooks as if weâre in for a bad storm,â Joe commented, and Frank put on speed.

A few minutes later the car was parked in the Hardysâ garage. They were mounting the steps of the back porch when the storm broke. Quickly Frank inserted his key in the kitchen door and turned the knob. At once the burglar alarm rang loudly and all the first-floor lights went on.

Joe chuckled. âThatâll bring Mother and Aunt Gertrude down in a hurry.â He flicked off the alarm.

âAnd bring the police, too,â Frank added. He picked up the kitchen phone and dialed headquarters. âThis is Frank Hardy. Our alarm went off by accident. Forget it.â

âOkay. You sure everythingâs all right?â the desk sergeant asked.

âYes. Thank you. Good night.â

By this time the two women had appeared and Mrs. Hardy said, âI didnât know the alarm was turned on.â

âWell, I did,â Aunt Gertrude spoke up. âI wanted to be sure to wake up and see how you boys made out. You must be starved. Iâll fix some cocoa and cut slices of cake while you tellâFrank, look at your clothes! Your jacketâs torn. And you, Joe, where did you get that lump on your forehead? And your facesâthe two of you look as if youâd been rolling in the dirt.â

âWe have.â Joe grinned. âHad a big fight. But we saved this!â He pulled the box from his pocket.

As the boys related their adventure, crashing thunder lent a booming orchestration to the story.

âThis is the worst storm weâve had in years,â Mrs. Hardy remarked. âIâm glad you boys didnât have to be out in it.â When Frank and Joe finished eating, she added, âAnd now you must get a good nightâs sleep.â

âBut first Iâd like to open Mr. Wrightâs box and see just what we have to guard so carefully,â Frank said.

Everyone watched excitedly as Joe unwrapped the package. Inside was a small transistor radio.

âIs that all it is?â Aunt Gertrude burst out. âYou risked your lives to get that?â

The boys were puzzled. Surely their father would not have made such a request if this invention were not unusually valuable.

âLetâs turn it on,â Frank suggested.

Joe clicked the switch. A man was speaking in Spanish from Madrid, Spain, and announcing the start of a newscast. His voice was very clear.

Frank grabbed his brotherâs arm. âDo you hear that?â he cried. âThe receiver is not picking up one bit of static!â

âYouâre right!â Joe agreed. âIt must be designed to work in the high-frequency bands.â

âBut how can we be receiving a broadcast direct from Madrid? That Spanish station must be transmitting by short-wave. Yet, weâre hearing it loud and clear. This is amazing!â

Joe gazed at the miniature radio with great interest. âIâll bet thereâs a lot more to Mr. Wrightâs invention than just being able to hear overseas stations without static,â he observed. âAfter all, why is he so anxious to keep it a secret?â

Just then there was a loud knock on the back door and a voice from outside said, âLet me in! Iâm a ham! I have a message for you!â

CHAPTER III

Warning Message

FOR a few seconds none of the Hardys spoke. They were trying to decide if the caller at the kitchen door really was a radio ham with a message. Or a member of the burglary gang?

Finally Mrs. Hardy said, âWe canât let the man stand out there in the rain.â

Frank called, âWhereâs the message from?â

âMr. Hardy in San Francisco.â

âOpen the door,â Mrs. Hardy said quietly.

Joe hid the box containing the invention, then he and Frank stood on either side of the door, poised for any attack. Aunt Gertrude had armed herself with a broom. Joe turned the knob and a water-drenched figure in raincoat and hat stepped into the kitchen.

âThanks,â the man said, removing his hat. âWhat a night! My wife told me I was crazy to come out.â

The speaker was an honest-faced man of about thirty-five. He noticed Aunt Gertrudeâs broom and smiled. âYou can put that away,â he said. âIâm harmless.â

Miss Hardy looked embarrassed. âTake off your coat,â she said. âIâll get you some coffee.â

The man nodded. âI could use it. I got cold walking over here. My car wouldnât start.â

âDid you come far?â Joe asked.

âAbout five blocks. Iâm Larry Burton, 69 Meadowbrook Road. Iâve always wanted to meet the Hardy boys. This all came about in a funny way. I have a short-wave set. Tonight I picked up your father. He said he couldnât get through to you or the police on the phoneâlines tied upâand you didnât answer his signal on your short-wave set.â

âWe werenât expecting a call,â Frank answered. He did not say that the boys had not been at home and that their mother and Aunt Gertrude rarely paid attention to the set unless specifically asked to do so.

âBy the time I phoned you, the lightning was fierce,â Burton went on. âMy wifeâs scared to death of lightning. She wouldnât let me use the phone, so I walked over.â

Aunt Gertrude served the caller coffee and cake as they all sat around the big kitchen table.

âWhat was the message, Mr. Burton?â Joe asked.

âThat you boys are in great danger. A gang is after you and will stop at nothing to get what they want.â

âHow dreadful!â Mrs. Hardy exclaimed. âDid my husband name thisâthis gang?â

âNo. Thatâs all there was to the message,â Burton replied. âIâm sorry to bring you bad news, but I guess thatâs to be expected in a detectiveâs family. Well, I must get along.â He stood up.

Frank shook the manâs hand. âWe sure appreciate this. Maybe some time we can return the favor.â

âForget it,â Burton said. âI only hope that gang doesnât harm you fellows.â

Joe helped him with his coat and he went out. The storm had moved off.

For a few minutes the Hardys discussed the caller and confirmed his address in the telephone directory. Joe was a bit skeptical, however. âEither he made up the whole story, or else Dad is really concerned for our safety.â

Frank was inclined to think Burton had told the truth. Had he and Joe already encountered two members of the gang at the Wright home?

Aunt Gertrude spoke up. âHow in the world did my brother Fenton hear this in California?â

âNews travels,â said Mrs. Hardy. âEspecially among detectives and police.â

âHmm!â Aunt Gertrude murmured, then announced she was going to bed.

Ten minutes later Frank and Joe were asleep and did not awaken until ten oâclock. At once Frank got up and opened a wooden chest of sports equipment under which he had hidden the box containing Mr. Wrightâs invention. It was still there.

âWhere do you think we should keep this?â he asked Joe as they were dressing. âDad said not to leave the box at home.â

âA tough problem, Frank. With that gang after us, we canât take the chance of carrying it around with us,â Frank answered.

âRight. And they may not be after us, but after the invention,â Frank answered.

While they were having breakfast, Frank came up with the idea of a unique hiding place for the invention. âLetâs put it in the well under the spare tire in the trunk of our car,â he said.

Joe laughed. âNow youâre using that old brain of yours. Best place you could have picked. The carâs vibrations canât hurt the radio and no one would think of looking there.â

Mrs. Hardy asked her sons what their plans were for the day.

âDad told us to drop into the antique airplane show and see if we could spot anybody who seemed overly interested,â Frank replied. âHe thought the person who stole Mr. Wrightâs old plane might be planning another theft.â

âTonight,â Joe continued, âweâre going to Chetâs party and stay until tomorrow. Okay?â

âOf course,â his mother answered.

Chet Morton, an overweight, good-natured schoolmate, lived on a farm at the edge of Bayport. A group of boys and girls had been invited there to a barn dance and late supper. Frank and Joe would pick up Callie Shaw, a special friend of Frankâs. His brotherâs date was usually Chetâs sister Iola.

Mrs. Hardy remarked that since the boys would be away, she would spend the night with a friend. âYour aunt plans to visit Cousin Helen in Gresham, anyhow.â

During the conversation Aunt Gertrude had left the table. She returned holding the local morning newspaper. âWell, you boys are in for real trouble!â she exclaimed. âListen to this!â

Miss Hardy read an account of the captured burglars at the Wright home and the mysterious summons to the police. The item stressed the fact that the menâs assailants, when caught, should be dealt with severely.

âWhen caught, eh?â Joe burst into laughter. âWeâre going to be mighty hard to find, arenât we, Frank?â

His brother grinned, but Mrs. Hardy looked worried. âMaybe you boys should explain everything to Chief Collig.â

âNot without Dadâs and Mr. Wrightâs permission,â Frank answered. âFor the time beingââ

âI havenât finished,â Aunt Gertrude interrupted. âIt says here that the police think this incident might be part of a gang feud.â She removed her reading glasses and gazed at her nephews. âYou two are now considered to be part of a gang and the rival gang is about to harm you.â

âWow!â said Joe, pulling his hair over his eyes and striking the pose of a belligerent âbad guy.â âWeâd better look the part!â

Since the antique airplane show did not open until two oâclock, the boys did various chores during the morning. They also hid Mr. Wrightâs invention in the tire well and bolted the spare back into place.

After lunch Frank and Joe drove Aunt Gertrude to the train. From there they went directly to the Bayport Air Terminal where the antique airplane exhibit was housed in the spacious lobby. The first person they saw was Chet Morton.

âHi, fellows!â he greeted them. âSay, take a look at those old planes. Arenât they beauties?â

âSure are,â Frank agreed. âI notice that most of them are biplanes. It must have been fun flying in the days of the open cockpits.â

âYou can say that again!â Chet declared. As he stepped back for a better view, his foot slammed down on the toe of a man standing directly behind him.

âOw!â the stranger yelped.

The boys turned to see the man hopping around on one foot. âYou stupid, overgrown kid!â he screamed.

âIâm awfully sorry,â Chet said apologetically.

The tall, muscular man, who had blond hair and hard features, looked at the youth menacingly. âYou idiot!â he snarled.

Frank and Joe stepped in front of Chet as he stammered, âWhoâwho are you calling an idiot?â

âNow just a minute!â Joe interrupted. âIt was an accident. No sense getting upset about this!â

âCan I be of any help?â the boys heard someone say. They looked around to see a lanky young man walking toward them. He had rust-colored hair and leathery skin that was deeply tanned.

âWhat are you butting in for?â snapped the stranger.

âThis boy didnât step on you intentionally,â the young man insisted. âI saw the whole thing. You were trying to listen to their conversation and got too close.â

The tall stranger was about to say something, but hesitated. For a moment he glared at Chet and his companions, then stomped out of the lobby, swinging his brief case.

Frank and Joe looked at each other. Why had the man been listening to their conversation? Did he belong to the gang they had been warned about?

Meanwhile, Chet was saying, âThanks for your help, Mr.ââ

âMy name is Cole Weber,â the young man introduced himself. âIâm president of the Central Antique Airplane Club. We own the exhibit and are taking it to several airports. Weâre trying to encourage public interest in vintage aircraft.â

âSounds like a great club,â Joe remarked.

âWe think so,â Weber said. âThe majority of the models you see here are replicas of real airplanes owned and operated by our members.â

âYou mean that some of those old crates still fly?â Chet asked.

Weber grinned. âWell ... we donât think of them as crates. When properly rebuilt, most antique planes are as safe and reliable as the day they were originally made. I own one myself. Itâs outside on the ramp. Would you like to see it?â

âWould we!â Joe exclaimed.

Mr. Weber led the boys to the airport ramp. A short distance ahead stood an orange-and-white biplane. The boys peered into the two open cockpits.

âThis is cool!â Joe declared.

The pilot smiled. âCompared to modern planes, mine doesnât have many instruments. But since we fly the antiques only for fun, we donât need elaborate equipment, such as that required for all-weather operations.â

The boys looked closely at the diagonal pattern of wires stretching between the wings. Then they examined the planeâs radial engine and the long, slender wooden propeller.

âHow many passengers can you carry?â Frank asked.

âTwo in the front cockpit,â Weber answered. âSay! Would two of you like to go for a ride?â

The boysâ eyes widened with excitement. Then Frank and Joe remembered the sleuthing they had promised to do for their father.

âThanks just the same,â Frank said, âbut Iâm afraid Joe and I canât go this time.â

âBut Iâd like to,â Chet spoke up. âSay, fellows, could you drive me to the farm afterward?â

âFarm?â Weber interrupted. âAre there any level stretches of ground in the area?â

âPlenty of them. Why?â

âIâll fly you home if youâd like.â

Chet tingled with excitement. âGreat! Thanks.â

The flier opened the baggage compartment and took out a parachute, helmet, and goggles. âPut these on and climb into the front cockpit.â

âMr. Weber, do you know Mr. Malcolm Wright?â Frank asked.

âYes, indeed. Heâs a member of our club.â

âDid you hear that his antique plane was stolen?â Joe put in.

Weber nodded. âToo bad. I understand he has some secret invention he was trying out in the plane. I hope that wasnât stolen too.â

The boys caught their breath in astonishment but said nothing. They had not heard this. Weber did not seem to notice. He donned his own parachute and summoned a mechanic to twirl the propeller and start the engine. Then he climbed into the rear cockpit.

âBrakes on! Switch off!â the mechanic called.

âBrakes on! Switch off!â Weber echoed.

The mechanic pulled the propeller through several times. Then he stepped back and yelled:

âContact!â

âContact!â the pilot responded.

The engine caught on the first try. A staccato popping developed into a steady roar. Chetâs goggled face turned toward the Hardys. He waved wildly as Weber taxied out for take-off.

âSee you at the party!â Chet shouted over the roar of the engine.

Minutes later the plane, looking like a box kite, was climbing above the Bayport field. As the Hardys turned to leave, Frank caught his brotherâs arm.

âThereâs that man Chet stepped on! Heâs watching us from the doorway! This time I mean to find out why.â Frank started to run. âCome on, Joe!â

CHAPTER IV

The Cold Trail

As soon as the man saw Frank and Joe, he turned to hurry off. In doing so, he hit the doorframe and dropped his brief case, which burst open. At a distance the boys could not read any of the printing on the letters that fell out, but one had red and blue stripes at the top.

The tall, blond man snatched up the papers and stuffed them into the brief case. He quickly zipped it shut and began to run.

âHe sure isnât on the level,â Joe remarked, âor he wouldnât race off like that. We canât let him get away!â

The strangerâs long legs and agility helped him cover a wide stretch in a short time. Before the Hardys could catch up to him, he reached the exit and jumped into a waiting car which zoomed off.

Frank and Joe stopped short, puzzled. Was the man afraid of them? And if so, why?

âMaybe that brief case had something to do with his running off,â Frank said.

The boys went inside the terminal building. They continued to look at the planes while keeping their eyes open for any other suspicious characters. They saw none and finally returned home.

âYou must be hungry,â said Mrs. Hardy. âI have hot apple pie, but itâs getting cold.â

Joe patted her shoulder. âShall we eat dessert first?â he teased.

Later the boys went upstairs to change for Chetâs barn dance. Both put on jeans, plaid shirts, and big straw hats. They packed overnight bags, then joined their mother who was waiting to be driven to her friendâs home.

Just before leaving the house, Frank heard a signal from their private short-wave set. âDad must be calling,â he said, and raced to Mr. Hardyâs second-floor study.

âFH home,â he said into the mike. âOver.â

âFrank,â said his father, âhowâs everything?â

âOkay, Dad. How about you?â

âFair,â the detective said. âBut I have a new lead to follow. You wonât be able to get in touch with me for a couple of days. Did you get my message from the ham operator?â

âYes, Dad.â Frank told him all that had happened in the past twenty-four hours, including the wiretapping.

Mr. Hardy whistled. âThen the gang knew where you were going.â

âShall Joe and I tell Chief Collig we were the first burglars?â Frank asked.

âI guess youâd better,â the detective agreed. âBut warn him the information is confidential and donât tell him what the invention is you were after.â

He now explained that he had been tipped off by Chicago police that a gang suspected of robbery there had suddenly vanished. A âsquealerâ had reported they were out to âgetâ the Hardy detectives. The boysâ father did not know why, but surmised it might concern Mr. Wrightâs invention.

âAnd now let me speak to your mother,â Mr. Hardy said.

Half an hour later Frank and Joe stopped at Chief Colligâs home and made their report. The chief burst into laughter. âSo youâre the ones who knocked out those men. I guess they had a real scare. They havenât talked since.â

By the time the boys reached the Mortonsâ farm with Callie Shaw, the dance was under way. A Bayport High School combo was playing.

âHi, masterminds!â Chet shouted as the Hardys strolled in. âI thought youâd never get here. Boy! Wait till I tell you about my flight!â He began to describe the adventure, supplementing his words with swooping motions of both hands.

His sister Iola joined Callie and the boys. She was a slim, dark-haired girl and very pretty. âHi, Joe, Frank, Callie!â Then hearing her brother, she said laughingly, âOh no! Is Chet talking about his flight again? He hasnât stopped since he landed.â

âYou just donât know anything about real flying,â her brother said, âuntil youâve been in one of those old biplanes.â

âOur turnâs next,â Joe reminded him.

The following hours passed quickly. When it was time for supper, Joe and Iola decided to eat outside. They filled their paper plates with sandwiches, chocolate cake and cups of lemonade, and went to sit on the steps of the Mortonsâ front veranda.

As they ate, Iola glanced toward the driveway in which many of the guests had parked their cars. The Hardysâ convertible was near the end of the long queue.

Suddenly Iola touched Joeâs arm. âWhatâs the matter?â he asked.

âI saw someone lurking behind your car,â Iola replied. âYes. There he is.â

Joe peered into the darkness. He saw a man, his hat pulled low, pop up from behind the car, then duck down again. At once the young detective sprang to his feet and ran toward the mysterious figure. The fellow might be after the secret radio!

âWho are you?â he shouted, seeing the trunk lid rise and the light go on. âWhat are you doing?â

The intruder ran from behind the car and disappeared into the darkness. Joe dashed after him.

âKeep your distance or youâll get hurt!â the man shouted. But Joe went on.

Iola screamed for help. Frank, Chet, and their classmates, Biff Hooper and Jerry Gilroy, raced from the barn.

âWhatâs wrong?â Frank asked.

âWe saw a man lurking behind your car,â Iola answered in a trembling voice. âJoe ran after him through the woods but was warned away.â

At once Frank and his companions rushed in that direction. The boys had not gone far when they heard a muffled cry for help, followed by the roar of a car speeding off.

Coming to a halt, Frank signaled to his friends for silence. The sounds of the car faded away. Everything was still, except the big grandfather clock in the hall of the Morton home. It began to strike. Midnight! Frank thought of what had happened just twenty-four hours earlier.

âJoe!â he shouted. âJoe! Where are you?â

His call went unanswered. The young detective stood frozen in his tracks. Had his brother become the victim of the gang?

By this time everyone at the party had raced outside to learn what had happened. They joined in a frantic search but without success.

âIâm afraid he was kidnapped,â Frank said grimly.

âIn the car we heard roar off?â Biff Hooper asked.

âYes.â

Jerry Gilroy chimed in, âBut by whom? And for what reason?â

âI donât know,â Frank said. He turned and rushed back to the convertible. Seeing the trunk open, he immediately looked in the tire well. The secret radio was still there.

âJoe must have blocked an attempted theft and been taken away so he couldnât identify the man,â Frank thought.

He slammed the trunk shut, asked his friends to guard the car, and ran to the house. He scooped up the telephone and dialed the home number of Chief Collig.

âWhat!â the officer exclaimed when Frank told him about Joeâs probable kidnapping. âIâll call the FBI and also get some of my own men out there right away! And Iâll come myself.â

He and three officers arrived shortly and were given a briefing. The place was carefully examined, but searchlights picked up little.

There was such a profusion of tire tracks on the main road that those of the mystery car could not be detected. Iola, the only one except Joe who had seen the suspect, could give little information other than that he was tall, heavy set, and wore gloves.

âThen we wonât find any fingerprints on your car,â the chief said to Frank.

Frank nodded. âHe could be the man who ran from Joe and me at the airport.â Frank told the police about him and gave a fuller description.

âWeâll be on the lookout for him, as well as for Joe,â Collig said. âThereâs nothing more we can do here, but Iâll leave two of my men.â

Solemnly the group left the barn dance and each guest expressed a hope for Joeâs speedy return. The Mortons tried to comfort Frank and discussed whether or not they should call Mrs. Hardy and tell her the disturbing news.

âI donât see that anything can be gained by that,â Chetâs mother said. âLetâs wait.â

She insisted Frank try to get some sleep, but he lay wide awake, hoping the phone would ring with good news from Collig. But none came. Chet, in the same room, was restless.

Finally at five oâclock he said, âWhere do we go from here?â

âIâm not sure.â Frank sighed. âWeâve absolutely no clue. In fact, we donât even have a description of the car we heard drive off last night.â

âJoe could be miles from here by now,â his chum remarked.

Frank thought for a moment. âLetâs drive down the road and make some inquiries at the farm-houses along the way. Thereâs a slim chance someone may have spotted the kidnap car.â

The boys left the house quietly and jumped into the Hardysâ convertible. They waved to the patrolling police guards. Frank drove along the narrow, tree-lined road. As they feared, all their inquiries were fruitless. Most of the farmers they questioned had retired long before midnight, and had neither seen nor heard anything.

âGuess we may as well go home,â Chet suggested.

But Frank was not ready to give up. âLetâs drive on a little farther,â he said.

About six-thirty the boys spotted a farmer cutting weeds by the roadside and stopped to question him. He rubbed his chin dubiously while listening to their story.

âQuite a few cars go past my place every night,â he said. âNow you come to mention it, there was an automobile come whizzinâ along and stopped here right after midnight. It woke me up, what with two men in it shoutinâ at each other.â

âDid you see the car?â Frank asked.

âNo. I didnât get up. Course my home is right beside the road, and I couldnât help but hear some oâ what the men were sayinâ. The car come along at a mighty lively clip, but when it got in front of the house, the driver slammed on the brakes and stopped.

âThere was an argument. I heard him tellinâ somebody they must have gone past the crossroads in the dark. The other man started jawinâ at him and they had quite a row. Finally they turned the car around and went back.â

âTo the crossroads?â said Chet.

âYes. Thatâs about two miles back.â

âI remember. One road goes to Gresham, the other heads up through the truck farms.â

Frank and Chet returned to the crossroads. But which way should they go? Right to the farms, left to Gresham?

âThe kidnappers might have hidden Joe on one of the truck farms,â Chet suggested.

âYes, except that all those farms are close together and everybody knows everybody elseâs business,â said Frank. âIâd rather tackle the road to Gresham. If we donât find Joe, we can come back and try the other road.â He took the turn to the left.

As they sped along, the boys spotted the wreckage of a black car in a roadside ditch. Afraid this was the kidnap car, Frank pulled up.

âSome accident!â Chet observed.

The license plates had already been removed from the badly smashed-up car.

âIf anybody was hurt,â Frank said, âtheyâll know it in Gresham. Weâll ask the police there.â

Suddenly a black sedan swung out of a lane some distance ahead and roared off toward the town. Frank stared fixedly at the rear seat.

âLook!â he exclaimed, gripping Chetâs arm. âDo you see what I see?â

âWhat?â

âA hand. Isnât that someone signaling?â

Chet gazed ahead and saw a hand wave frantically for a moment at the rear window, then suddenly withdraw.

âYouâre right!â Chet snapped. âJoe!â

Frank started the convertible and sped off in pursuit.

The other car had a good lead and was increasing speed. It was almost obscured by a cloud of dust, but Frank memorized the out-of-state license number.

âWeâre gaining on them!â Chet declared.

Frank nodded. Inch by inch the intervening distance lessened. Trees, farms, and hedges flashed by. At times the boys could hardly see the sedan through the swirling clouds of dust.

Suddenly the steady hum of the convertibleâs engine changed its rhythm. The motor sputtered.

Chet groaned. âNow what?â he muttered as the car slowed down.

The boysâ hearts sank when the engine quit completely. They looked dismally at the other car as it disappeared around a distant bend in the road.

CHAPTER V

The Hunt

FRANTICALLY Frank flung open the hood and examined the engine. In a few minutes he discovered the trouble.

âFuel pump,â he announced.

âOhâoh!â Chet sighed. âAnd weâre miles from a service garage.â

âWeâre not stranded,â Frank assured him. âI suspected the pump was going so I put a spare in the trunk. But itâs going to take fifteen or twenty minutes to change the pump, andââ

âAnd by that time the kidnap car will be far away,â Chet finished.

âIâd better notify Bayport Police Headquarters.â Frank turned on the carâs two-way radio to the proper frequency and gave the license number of the suspectâs car.

âWeâll get busy on it right away,â came the answer. âIncidentally, FBI men have been here and out to the Morton farm. Iâll contact them. Thereâs no news so far.â

Frank replaced the mike. He and Chet worked feverishly to install the new fuel pump and soon had the engine running.

âNo chance of our catching up with the sedan now,â Chet remarked as the boys once again got under way. âIt has nearly a half hourâs head start.â

âIâll bet that the kidnappers wonât stop at Gresham, now that theyâve learned weâre after them.â

Ten minutes later Frank stopped the car. He backed into a side road, pulled out again, then turned to retrace his route. âI want to go up that lane the kidnap car came out of and see what we can find.â

Reaching it, Frank turned in. The ground was stony and full of holes. Progress was slow.

Half a mile farther on, an old inn, apparently closed, came into view. It was a long, low white building with a wide veranda. The boys got out of the car and Frank knocked several times, hoping someone might be inside. There was no response.

âNobodyâs home,â Chet mumbled.

Just then the sound of heavy footsteps could be heard. The door sprang open and a surly-faced man confronted them.

âWhat is it?â he growled.

âSorry to bother you, sir,â Frank said, âbut have you seen a black four-door sedan within the past hour?â

âYouâve got nerve waking me up to ask such a stupid question!â the man snapped. âI donât know anything about a sedan!â

âHave you had any visitors recently?â Frank persisted. âThereâs a wrecked car lying in a ditch close to the spot where your lane leads in from the road. Did anyone come here for help?â

The man looked at the boys suspiciously. âGet out of here before I kick you off the porch!â

âHave it your way!â Frank retorted. âIâm certain there were kidnappers in that sedan I asked you about. If you know anything, youâd better tell me, or be held as an accessory!â

âKidnappers?â the man cried out. âOkay! So there were some guys walked in here late last night.â

âHow many were there?â Frank demanded.

âThree. One said theyâd had an accident, and asked if they could stay at my place for a while. They paid me real good, so I let âem come in.â

âPlease describe these men.â

âOne was tall, one short,â the proprietor replied nervously. âThe big guy said theyâre brothers named Wagner. They were carrying the third guyâhe was wrapped in a blanket âcause he got knocked out. I couldnât see his face. The big guy made a telephone call to Gresham. A car picked âem up about an hour and a half ago. I canât tell you any more!â

He stepped back inside the house and slammed the door in the boysâ faces.

âSociable guy,â Chet commented as the boys drove off.

âHe did give us one lead,â Frank said. âThe wreck was theirs and the pickup car came from the direction of Gresham. Chet, Iâm afraid Joe was hurt. Weâre going to Gresham. Iâll call Collig and tell him what we just heard.â He tuned in Bayport headquarters and left the message.

On reaching Gresham, Frank cruised up and down the side streets flanking the main boulevard, hoping to spot the sedan but had no luck. He then headed for the local police headquarters. âDad introduced me to Police Chief Stanton when we were passing through this town several months ago,â he said.

The boys entered the neat, red-brick building and Frank introduced himself and Chet to the desk sergeant on duty. They were ushered into the office of the chief.

âFrank Hardy, how are you?â Stanton said, extending his hand in greeting. âSit down.â

âHas Chief Collig in Bayport been in touch with you?â Frank asked.

âYes. So far we have no word on the sedan or the men traveling in it, one of them injured. Youâre sure your brother was kidnapped?â

âGet out of here!â the man growled

âWithout a doubt!â

âHmm!â Stanton muttered. âThe sedanâs probably miles away by now with a different license plate. But our men will keep on the lookout.â

Realizing they could do no more here, Frank and Chet decided to return to Bayport.

âWhatâs our next move?â Chet asked.

âWhoever kidnapped Joe might ask for ransom, Chet. Iâd better stick close to the phone at home in case someone tries to establish contact.â

Then Frankâs heart sank as he thought of having to tell his mother and father and aunt that Joe was missing! When he pulled into the Hardy garage some time later, Frank shut off the ignition and sat quiet for several seconds. Then he took a deep breath and climbed out of the car.

He had no sooner entered the house when Mrs. Hardy rushed to meet him. âWhat happened to Joe?â she cried.

Frank was startled by her question. Before answering, he hugged his mother and led her into the living room.

âI just got home, and decided to telephone the Morton farm. I spoke to Iola,â Mrs. Hardy explained. âShe seemed terribly upset and started to tell me something about Joe, then stopped. She said you were on your way here and would explain.â

Frank related the whole story of Joeâs disappearance. Mrs. Hardy was stunned by the news and tears filled her eyes.

âI would have told you sooner,â Frank said âbut I was hoping to find Joe before this.â

Although Mrs. Hardy worried about the dangers involved in her familyâs sleuthing activities, she rarely displayed her concern openly. But now she could not hide her anxiety. She began to tremble.

âWe must do something!â she pleaded. âHave you notified the police?â

âYes,â Frank answered. âAnd the FBI.â

âYour father! He should be told about this at once!â

âBut we canât reach him,â Frank reminded her.

The hours dragged on into early evening. Mrs. Hardy continually walked the floor, saying over and over, âThis is dreadful, dreadful!â

Frank paced around nervously, mulling over in his mind the events that had taken place during the past two days. The telephone rang. Was it the kidnapper calling? Frank rushed to answer the call.

âFrank, this is Chief Collig!â

âYes, Chief! Any news?â

âNot much. The police managed to detect the scratched-off serial number on the engine block of the car lying in the ditch. It was traced through the State Bureau of Motor Vehicles. The car was stolen yesterday evening from a man in Lewiston. No one saw the thief.â

âWell, weâre right back where we started,â Frank said.

After a light late supper, Frank settled himself into a wing chair within reach of the telephone. The hours ticked by with no word from Joe or his abductors. Finally, through sheer exhaustion, Frank dozed off.

When he awoke, the sun was already sending bright, warm rays into the room. Frank got up and began to pace back and forth. He and his mother ate a sketchy breakfast. They grew more uneasy when the morning passed without any news of Joe.

Shortly after noontime a taxi stopped in front of the Hardy home. A tall, angular woman, carrying a small suitcase, got out of the cab and hurried toward the house.

âItâs Aunt Gertrude,â Frank announced to his mother.

âIâm glad to be home!â Miss Hardy exclaimed as she entered the house like a rush of wind.

She glanced at Mrs. Hardy and immediately sensed that something was troubling her. âLaura! You look exhausted. Havenât you been getting enough sleep? Whatâs wrong?â

âWe have something to tell you,â Frank declared. âYouâd better sit down.â

He broke the news about Joeâs disappearance as gently as he could. His story, however, sent Aunt Gertrude springing from her chair.

âThatâs terrible! Poor Joe! Call the police!â she cried. âCall the FBI! Do something!â

âTry to be calm,â Frank pleaded. âThe police and the FBI have already been notified.â

âI felt it in my bones!â Aunt Gertrude exclaimed. âSomething like this was bound to happen.â

âNow, Gertrude, please,â Mrs. Hardy interrupted.

Aunt Gertrude continued to rattle on. âYou canât be too careful these days. The world is full of rude and nasty people. Now you take this morning, for example, when I was walking on the platform at Gresham. Suddenly this big fair-haired man stepped right in front of me, carrying a bulging brief case. Part of its zipper was torn and some of the papers inside were sticking through.

âWell, this clumsy ox gave me a hard bang on my arm with that dirty, beat-up brief case. I was about to give him a piece of my mind, when he deliberately pushed me aside!â

Her words had seized Frankâs attention. The man sounded like the one that Chet had stepped on in the airport terminal and Frank and Joe had chased later. He might be one of the kidnappers! The suspectsâ car had gone toward Gresham!

âThen came the crowning insult,â she went on. âHe called meâhe called meâan old whaler! Can you imagine? I never fished for a whale in my life! Next, this big fair-haired lummox walked over to two other men and handed them the brief case,â Aunt Gertrude continued. âI was so furious, I decided to demand an apology. I went up to the big man and tapped him on the shoulder. He must know me because just then he said âHardy.â Well, he turned and glared at me, then hurried off with his friends. The nerve, indeed!â

Frank had already jumped to his feet. He was obviously excited. âDid you see what was written on the papers in the brief case?â

âI wasnât close enough to read them. But one had red and blue stripes on it.â

âHeâs one of the men we suspect!â Frank cried out. âAunty, did you hear any more of the menâs conversation? Anything at all?â

âNo, not really,â she answered, somewhat puzzled by her nephewâs questioning. âI only caught a word or two. The fair-haired man said something about caves. Yes, thatâs itâcaves! I remember because it struck me at the time that with his bad manners, he should be living in one.â

Frank darted to the telephone and called Chet. âIâm sure Iâve latched onto an important lead,â he told his chum. âIâll need your help.â

âIâm ready to go any time you say.â

âOkay! Iâll be right over!â

CHAPTER VI

Fogged In

FRANK leaped into the convertible and headed for the Morton farm. He began piecing together the details of Aunt Gertrudeâs story about the fair-haired man at Gresham. He had said, âHardy!â

âIâm sure he didnât mean Aunt Gertrude. He could have meant Dad or Joe!â

Then the man had made a reference to caves! There were many to be found in the cliffs which formed the north shore of Barmet Bay. Was Joe being held in one of them? Frank smiled, recalling his auntâs indignation at being called an âold whalerâ by the big fair-haired man.

âHe might not have been referring to whales at all,â Frank thought. âThereâs a small, flat-hulled motorboat known as a motor whaler. Maybe thatâs what he had in mind.â

Frank told himself that using such a term would be unusual for any person unless he was familiar with boats. The young sleuth was certain that he had a real lead at last!

As Frank drew up before the Morton house, Chet came down the steps on a run. âWhatâs up?â he asked eagerly.

Frank repeated Aunt Gertrudeâs story of the man mentioning the name Hardy and making the mysterious reference to whaler and caves.

Chet whistled, then suddenly his eyes widened. âYou mean Joe might be a prisoner in a shore cave?â

âExactly!â Frank answered. âAnd Iâll search every one of them if I have to!â

âIâm with you! How about the other fellows? Letâs get Biff and Jerry to come along. Theyâd be mad as hornets if they werenât in on the search.â

âOkay!â Frank replied. âWeâll use the Sleuth.â This was the Hardysâ sleek motorboat.

âLetâs go!â Chet said briskly. Then the ever-present problem of food occurred to him. âIf youâll wait a few minutes Iâll ask Mom to fix up a lunch for us. We may get hungry. At least you may, but Iâm sure I will.â

Both boys dashed into the house. While Mrs. Morton was making up a package of sandwiches and cake, Frank reached Jerry and Biff by telephone and gave them an inkling of what was afoot. They were eager to help and promised to be at the Hardy boathouse within twenty minutes.

In a short time Chet was ready and scrambled into the convertible beside Frank. At the boathouse Jerry and Biff were waiting for them. Biff was a tall, lanky blond whose perpetual good humor was indicated by the slight tilt to the outer corners of his lips. Jerry, medium height and dark, was wiry and more serious. Both boys were agog with curiosity.

âWhatâs the clue?â Jerry asked, and Frank gave the details as he unlocked the door of the boathouse.

The boys quickly unmoored the Sleuth and jumped aboard. The engine sputtered spasmodically a few times, then burst into a roar. Frank opened the throttle and the craft shot into the bay, gradually increasing speed.

âIf we donât find Joe, then what?â Jerry asked.

Frank answered promptly, âGo down the coast tomorrow. There are a few caves along the beach. You fellows game?â

âYou bet,â they chorused.

There were clouds in the sky and far off toward the open water at the distant end of the bay was a hint of fog. Frank eyed the mist doubtfully. It would take some time to make a close search of the caves on the north shore, and if fog came up, a hunt would be difficult. Chet, thinking the same thing, mentioned it aloud.

âWeâll just have to hope for the best,â Biff spoke up.

As they zipped along, the boys talked over Miss Hardyâs encounter with the fair-haired man.

âHe may be tall,â said Biff, âbut he sure sounds short on brains!â

âHeâll need all the brains he has if we get on his trail,â Chet affirmed.

âBut why would he be mixed up in Joeâs disappearance?â said Biff. âSurely he wouldnât kidnap Joe just because Chet stepped on him.â

âThereâs something deeper behind it,â Frank said, thinking of the secret radio, âbut Iâm not at liberty to tell you fellows. Sorry.â

The Sleuth sped on toward the north shore and gradually drew closer to the high cliffs that rose sheer from the waters of the bay. The fog was coming up the bay now in a high, menacing gray wall.

Chet grimaced. âWeâre not going to make it. That fog will be on us before we get within a quarter of a mile of the caves.â

âIâm afraid so,â Frank said. âBut I hate to give up now that weâve come this far.â

âIâve had a few experiences in fog out on this bay,â Biff Hooper remarked, âand I donât want to repeat âem if it can be helped. You never know when some other boat is going to come along and run you down. You canât see it until the boatâs right on top of you. Let one of those big ships wallop you and youâre done for!â

âA horn isnât much good,â said Jerry, âbecause the fog seems to make the sound come from a different direction than the true one.â

The fog swirled down on the boys, hiding the shore from view. It enveloped them so completely they could scarcely see more than a few yards ahead. Frank had already turned on his yellow fog light and suddenly they saw a small tug a short distance up the bay. The craft was heading toward the city, but now it vanished. Frank reduced speed and pressed the horn. No sound!

âThis,â said Jerry, âis bad. If it werenât for Joe, Iâd say go home. I wonder how long the pea soup will last.â

No one ventured a guess. Frank said tensely, âWatch for that tug, fellows. My horn wonât blow.â

As the Sleuth groped blindly through the clammy mist, Frank thought he heard the faint throb of the tugâs engines. His light did not pick up the craft and it was impossible to estimate its distance or direction.

Then came the blast of the tugâs whistle, low and mournful through the heavy fog. It seemed to be far to the right, and Frank hoped to avoid it by going straight ahead.

When the whistle sounded again, it was louder and seemed to come from a point just to their left. It was drawing closer!

âThat old tug must have traveled about two miles clean across the bay in half a minute,â Chet remarked. âFrank, 1-look out!â

As he spoke, the whistle sounded again. This time Biff straightened up in alarm. The tug seemed to be directly ahead.

âHow do you figure its position, Frank?â

âI think the tug is mighty close. Itâs hard to tell where the soundâs coming from. Weâll just have to go easy and hope we see it first.â

Biff could hardly make out the stern of the Sleuth. âThis is worse than a blackout,â he commented.

Once more the whistle blew, this time so terrifyingly loud that the tug seemed to be only a few yards away. The boys could hear its engines. Still their light revealed nothing.

âUp in front, Chet!â snapped Frank. âIf you see it, sing out!â

Chet scrambled onto the bow and peered into the gray gloom ahead. Suddenly he gave a yell of terror.

âItâs bearing right down on us!â

Even as he shouted, a heavy dark shadow loomed out of the fog. The Sleuth was about to be rammed!

The tug was sweeping down on the boys. It was only a few yards away! The boys could see a man on deck, waving his arms wildly. The whistle shrieked.

No time to lose! The engine of the Sleuth broke into a sudden clamor as Frank opened the throttle wide. At the same instant he swung the wheel hard to port. The motorboat swerved and shot directly across the bow of the larger boat.

For a breathless second it seemed that nothing could save the boys. They waited for the jarring impact that seemed only seconds away!

But the Sleuth had speed, and Frank handled his craft masterly. His boat shot clear!

The tug went roaring astern. It had missed the Sleuth with less than a yard to spare! The Hardysâ boat was caught in the heavy swell and pitched to and fro, but rode it out.

Chet Morton broke the silence. âWow, that was a close call!â

Jerry Gilroy, who had been thrown off balance when the Sleuth altered its course so suddenly, scrambled to his feet, blinking. âIâll say! Were we hit?â

âWeâre still here.â Biff grinned. Nevertheless, he had been badly frightened. âThatâs the last time Iâll ever come out on the bay when thereâs a fog brewing,â he announced solemnly. âThat was too narrow a squeak!â

Chet, now that the peril had passed, leaned down from the bow. He shook hands with the other three boys, then gravely clasped his own.

âWhatâs that for?â Jerry asked.

âCongratulating youâand myself on still being alive.â The others smiled weakly.

Frank steered the Sleuth back to its previous course. Again the boat crept toward the north shore, invisible beyond the wall of mist. Frank did not dare venture close for fear of piling his craft onto the rocks at the foot of the cliffs. He cruised aimlessly back and forth, but within half an hour the fog began to lift. It thinned out, writhing and twisting like plumes of smoke.

âThe cliffs!â Chet cried in relief as the boys caught sight of the land rising sharply just ahead. They were less than two hundred yards off shore and already far down the bay, abreast of the caves.

âWe can make our search after all,â Frank said.

He brought the Sleuth as near the base of the cliffs as he dared, skillfully avoiding the menacing black rocks that thrust above the water.

Jerry, who had scrambled out on the bow, gestured toward an outcropping of rocks about a hundred yards away.

âHereâs our first cave,â he announced.

âI remember it,â said Frank. âJoe and I went into that one when we were on a car-theft case. It looks like a cave, but is only a few feet deep. No use looking here.â

The searchers passed several shallow openings, but at last Chet gave a jubilant shout. âHereâre the deeper ones!â

They had rounded a little promontory and the boys saw a ragged row of gaping holes in the face of the rock. Most were just a few feet above the waterline.

Chet said, âI know them. Some are small but others are big enough for an elephant to walk through sideways.â

Frank brought the Sleuth in still closer to the base of the two-hundred-foot-high cliffs.

âGreat place to hide someone,â Biff commented. âI bet there are hundreds of those caverns.â

âWe have our work cut out for us,â Frank agreed.

Some distance on, he spotted the first of the larger holes in the rock. The cave was six feet wide and high above the water. Frank ran the boat in close enough so that by scrambling over its bow one could land on the tumbled heaps of rocks and boulders just beneath the opening.

âLetâs take a look,â he said eagerly. âJerry, will you hold the boat here?â

âSure. Go ahead.â

Within a few minutes the others were climbing up the boulders toward the cave mouth. Presently they vanished into the dark interior.

CHAPTER VII

The Escape

JERRY held the nose of the Sleuth inshore and maneuvered so that the propeller remained in deep water. He waited impatiently for news of Joe.

It did not take the others long to find that the big cave they had entered was unoccupied. They reappeared a few minutes later.

âDid you find him?â Jerry called.

âNo luck,â Biff reported.

Chet was discouraged and said so. âWeâre working on the slimmest of clues,â he said. âThe fair-haired man and his friends might not have meant the Shore Road caves. Donât forget, there are hundreds of subterranean caverns between Gresham and Bayport.â

âBut the caves here are the best known,â Frank remarked. âLetâs look some more. Iâll cruise along the shore and pick out the more likely caves to hide a prisoner.â

The motorboat edged its way along the face of the cliff. Whenever the boys noticed one of the larger openings that could be reached easily from the shore, Frank ran the boat in among the rocks. Then, while one boy stayed in the Sleuth, the others would scramble up to investigate the cave.

The hours dragged by. Finally they navigated to a place where the cliff sloped and began to give way to sandy hills and wooded inclines.

Biff gave a sigh. âGuess weâll have to give up. Thereâs only one small opening left to investigate.â

âBut why would kidnappers go way up to that cave when there are so many that are easier to reach?â Chet protested. âTheyâd have to climb fifty feet up to the mouth.â

âIt isnât so steep as it looks,â Frank remarked thoughtfully. âAnd I can see a sort of winding trail up the slope.â

âIâm game,â Jerry said.

âMe too,â Biff added.

Frank brought the Sleuth in toward the rocks. The boys craned their necks to look up at the tiny opening in the face of the cliff above.

âI guess youâre right, Chet,â Jerry admitted. âJoeâs kidnappers wouldnât climb all the way up there, with so many better caves to pick from.â

Chet gave a loud groan. âIâve lost about three pounds already, climbing these cliffs.â

Despite the worry over Joe, Biff could not refrain from saying, âThen, Chet, youâd better tackle about fifty more caves.â

Frank, meanwhile, had seen something that had gone unnoticed by his friends. A piece of newspaper was lodged among the stones under the caveâs mouth. The scrap of paper might be significant! The fact that it was within a few feet of the cave was suspicious and warranted investigation.

This time Chet volunteered to stand watch and maneuvered the boat around so the others could reach the shore from the bow. Frank went first. Biff and Jerry followed.

They climbed the slope, following the trail Frank had spotted. But the incline was so steep and winding that they could make only slow progress in a diagonal direction. The path ended abruptly at a ledge some fifteen feet below the cave. From there they had to climb directly upward over the rocks.

When Frank reached the piece of newspaper, he picked it up. The sheet was wet and soggy from the fog, but he recognized it as a copy of the Gresham Times, dated the previous day.

His hopes rose with this discovery. Gresham! For the third time since Joeâs disappearance the name of that town had come into the mystery! Excited, Frank thrust the paper into his pocket and scrambled up toward the entrance of the cave.

âWhat did you find?â Jerry demanded, panting.

âNewspaper. It looks like a clue.â

Frank reached the cave mouth and stepped inside. The interior was larger than he had thought. Though the entrance was small, the cave widened and seemed to be very deep.

The young detective took a flashlight from his pocket and clicked it. He played the beam on the rugged, rocky walls, the fairly level floor, and finally focused on a wooden box like those used for shipping food.

âSomeoneâs been here!â he shouted eagerly as the others entered the cave. âLook at that box! Fresh bread crusts around it!â

âDonât see anyone now,â Jerry observed. âListen!â

The boys heard a peculiar sound, which seemed to have come from the back of the cave. The sound was repeated. They listened, staring at one another in surprise.

âSomeoneâs groaning!â Frank exclaimed.

Biff pointed a trembling finger toward a large section of rock about twenty feet away. âFrom there.â

Again they heard groaning.

âSomebodyâs behind there!â Frank declared.

He ran toward the mass of rocks and directed the light into the shadows beyond. Frank gasped as its radiance fell upon a figure lying bound and gagged on a crude pallet of sacking.

âJoe!â Frank shouted. He sprang forward and removed the gag.

His brother answered feebly, âFrank!â

Biff and Jerry gave a joint yell of delight. They scrambled in behind the wall of rocks and bent over their friend.

Joe looked white and ill. He could scarcely talk to them. His feet were bound together with rope and his hands were tied behind his back.

âTo think that we werenât going to search this cave at all!â Biff exclaimed. âAnd wait until Chet learns we found you. Heâs down guarding the Sleuth.â

Frank had already opened his pocketknife and was hacking at the ropes that bound his brotherâs ankles. Jerry was working at the other knots.

âIâm hungry,â said Joe, when all the ropes had been loosened and he was able to sit up. âI havenât had anything to eat since yesterday noon.â

The boys helped him to his feet. âThey drugged me,â Joe went on shakily, âand I can still feel the effects. But tell me, how did you find me?â

âAunt Gertrude gets the credit.â Frank quickly told of her encounter with the fair-haired man at Gresham, and his reference to âHardyâ and âcaves.â

âBut Frank put two and two together,â Biff spoke up, and mentioned the newspaper clue.

âIt was lucky for me you saw the paper,â Joe declared. âOne of the kidnappers had some food wrapped in a newspaper yesterday. He must have dropped one of the sheets.â

âWas the big fair-haired man really mixed up in it?â Frank asked.

Joe nodded. âHe was in it, all right. But there were others. They were after that secret in our car. Itâs a long story. Let me tell you about it later.â

The boys refrained from asking more questions.

âDo you feel strong enough to come with us now?â Frank asked.

Joe, with a flash of spirit, started to walk. He wavered a moment and would have fallen if Frank had not caught him.

âIf you canât make it, weâll carry you,â Jerry offered.

Joe shook his head and sat down weakly. âMy legs are so numb from being tied up, I donât seem to have any strength in them. Iâd better wait a few minutes.â

At that moment they heard a loud noise. It was a clattering, rolling sound, as if a rock had been dislodged and gone tumbling down the steep incline.

âWhat was that?â Biff whispered.

Joe got to his feet. âMy captors are coming back! Quick! Weâll have to clear out!â

âCan they get in here through the rear of the cave?â Frank wanted to know.

âYes, a passage leads down from the top of the cliff.â

Frank and Jerry each slipped an arm around Joeâs shoulders and helped him toward the mouth of the cave. Biff ran on ahead.

When Chet saw Joe, he gave a war whoop of joy. The others motioned frantically for silence, but their jubilant chum did not understand their urgent signals. He proceeded to put on a noisy celebration. He yelled, waved his arms, and then, to their horror, began whistling shrilly.

The men coming down the passage into the cave would certainly hear the commotion and hurry to investigate. The boys must flee quickly!

Frank and Jerry scrambled down the slope with Joe. They reached the first ledge in safety, with Biff slipping and sliding along the path ahead of them. As they commenced the second half of the descent the boys heard a yell behind them.

Frank looked back. A man was standing at the mouth of the cave. He glared at the boys a moment, then turned and shouted to someone behind him. Two other men quickly joined him.

âGo on!â Joe cried. âIâm holding you up! If they catch us, weâll all be in trouble.â

âLeave you, my eye!â Jerry growled.

By this time Biff had nearly reached the boat. He called out to Chet, who apparently had not seen the men in the mouth of the cave. At Biffâs warning, Chet stopped his noise. Frank and Jerry clung to Joe on the narrow path, with loose rocks sliding treacherously beneath their feet.

Frank glanced back again. One of the men had drawn a revolver from his pocket and was pointing it at them. Another had stooped and was snatching up stones.

The revolver barked. A bullet whistled overhead. Frank and Jerry ducked and almost lost hold of Joe. A heavy stone hurtled past them and splashed into the water beside the boat.

A hail of stones followed. The man with the revolver fired again and again and several bullets came dangerously close to their mark.

Chet had revved up the engine, ready to take off as soon as his passengers climbed aboard.

âHurry!â Biff yelled. âOnly a few yards more!â

Frank and Jerry scrambled to the bottom of the incline with Joe. One of the three men was stumbling down the path in pursuit.

Jerry leaped onto the bow. With Frank on the shore and Jerry helping from the boat, Joe was hauled aboard. Frank was about to jump onto the bow when he felt a heavy, sharp blow on his left leg. He lost his balance and fell partly into the water. When he tried to rise, his leg doubled beneath him. One of the rocks hurled by the men had found its mark!

Shots sounded again. A splinter flew from the bow of the boat.

âHurry, Frank!â Chet urged.

âGive me a hand,â Frank said grimly.

Biff scrambled over the side, seized Frank, and laid him on deck. Frankâs leg throbbed and he could scarcely keep from crying out.

The man on the path was only a few yards away now! He showered the air with rocks!

CHAPTER VIII

An Astounding Report

SMACK! A large rock hit the water with a resounding crash only inches from the Sleuth. A deluge of spray drenched the boys.

Chet, at the helm, could hardly see. Wiping the water from his eyes, he gunned the motor and took off. The Sleuth made sternway from shore.

âGadzooks!â cried Jerry, mopping his face and looking toward the kidnappers. âTheyâve gone!â

âThey sure disappeared in a hurry,â said Jerry. âI wish we could have captured them. Frank, howâs your leg?â

âOh, itâll be all right, but it sure hurts.â He gave a wan smile. âNever mind that, though. The main thing is we found Joe.â

âYes, thank goodness,â his brother said weakly.

Chet had taken the Sleuth into deep water and was now speeding toward Bayport. Jerry and Biff were busy trying to make Frank and Joe comfortable on one of the long seats.

âTo think I missed finding Joe!â Chet said in disgust. âI climbed those cliffs every other time and searched. When Joe was found, where was I? Sitting in the boat!â

âGood thing you were,â Jerry retorted. âItâs lucky for us someone was here to have the Sleuth ready for a fast getaway.â

âWhy did it have to be me?â Chet complained. âSome fellows have all the luck. Joe, tell me about your capture. Who were those men who shot at you and heaved all those rocks? When did they take you to the cave?â

âBetter let Joe rest awhile,â Frank advised.

âI think we ought to go back and clean up on that gang!â Jerry put in.

âIâd like to learn more about them myself,â Frank said, âbut I think weâd better leave it to the police. Those kidnappers are a tough outfit, and we have Joe to look after. Heâs in bad shape. We should get him home.â

âHe looks hungry,â Chet observed sympathetically, as Frank tuned in their radio and called police headquarters to report the rescue.

Joe opened his eyes. âYou bet Iâm hungry.â

Chet grabbed the package of sandwiches he had brought with him and handed them to his chum. âI knew these would come in handy,â he said. âDig in.â

âHold it!â Frank warned. âNo solid food until the doctor says itâs all right.â

âThen how about the milk in this Thermos?â

âOkay.â

Joe drank the milk slowly and gratefully while Jerry satisfied Chetâs curiosity about their experience in the cave rescue.

Chet whistled. âThat was a close squeak.â

When the Hardys reached home, their mother was overwhelmed with relief at seeing Joe safe.

Aunt Gertrude hugged her nephew and said, âWell, this time you deserve sympathy. At least you didnât do something harum-scarum and propel yourself right into a mess of trouble.â

Dr. Bates, the family physician, was summoned to examine the young detectives. âNo internal damage,â he declared. âJust exhaustion. Joeâll be fit in just a day or two. Frank has a deep bruise which will be sore for a while.â

Joe was given a steaming bowl of hot soup, then put to bed. He immediately fell asleep.

Frank related the story of the rescue and gave Aunt Gertrude credit for the clue. She smiled and blushed but said nothing.

It was not until late that evening, after he had been refreshed by a long, sound sleep, that Joe was able to tell the others what had happened to him. He still looked pale, but good food and rest were beginning to do their work and a trace of color had returned to his cheeks.

âAs you know,â he said, âat Chetâs party I chased into the woods after that man who was looking in our car trunk. As I got near, someone reached out and grabbed me. I couldnât see his face.â

Joe said a gag had been jammed into his mouth and a hand clapped over his mouth. Then he was dragged to a car.

âMercy!â exclaimed Aunt Gertrude.

âBut why did he kidnap you if he was only after the secret radio?â Frank asked.

âThereâs another reason,â Joe replied. âIâll come to that. When we got to his car I tried to fight him, but heâs strong as an ox and managed to tie me up and put me in the back seat.

âThen he drove away. We went down the road for some distance and stopped. Two men came out of the bushes and walked over to us. One said, âIs that you, Gross?â and my captor growled at them, âNo names.â When they saw me in the car, the men wanted to know who I was. It seems they didnât know Gross was going to kidnap me.â

Joe said there had been a row about it. The other two men had wanted Gross to bring him back, but he was stubborn. âThis kid knows too much,â Gross had said. âHe saw the rocks. Besides, his father is a detective.â

âThe other men called him a fool and said he should have left me alone and let the other thing go.

âOne of them told Gross they didnât want the authorities after them for kidnapping. Then they realized it was too late to let me go, because there would be trouble when I got back to Bayport and told my story.â

Joe said that the two men got into the car and they all rode for about two miles. Then one of the men climbed out and headed across a field toward the bay.

âWe went on, but we hadnât gone far when Gross lost control of the wheel and we crashed into a ditch. The car was wrecked but no one was hurt. Gross and the other man seemed worried because they were afraid somebody would come along and find them. They took off the license plates.

âGross knew there was an old inn nearby. They agreed to go to it and telephone a friend of theirs to bring a sedan. They took a blanket out of the car. We walked up the road and into a lane where the inn was. Without any warning one of them slugged me from behind.â

Frank said, âAnd put you in the blanket.â

Joe said that later, as he started to come to in the inn, a drug was forced into his mouth and he was made to drink some water. He passed out, and did not wake up until morning, when they were carrying him in the blanket to their friendâs sedan.

âJust as we drove out of the lane and onto the Gresham road,â Joe continued, âI heard a car coming and managed to raise up. It looked like ours, so I tried to signal. Then Gross shoved me down.â

Joe had been driven to Shore Road and taken to the cave through an abandoned shaft.

âYou were there nearly two whole days!â Frank said.

âMost of the time I was alone. They fixed up a few sacks for me to lie on, but they didnât pay much attention to me. Once in a while they would bring in sandwiches and water and feed them to me.â

âDid you find out what theyâre up to?â Frank asked.

âAt night, when they thought I was asleep, I overheard enough to learn one of the gangâs secrets. Theyâre smugglers!â

Aunt Gertrude opened her mouth wide. âSmugglers!â she gasped. âWhat kind?â

âDiamonds and electronic equipment. Thatâs probably why they wanted to get Mr. Wrightâs special radio.â

Joe paused and Mrs. Hardy asked if he were too tired to go on. âNo, Iâm okay, Mother. I also learned that one of the top men is named Chris. From what was said, Iâd guess heâs that big fair-haired man whoâs been watching us.â

Frank was excited by this news. Now they had something definite to go on! If Joe were right, they could concentrate on finding Chris and turning him over to the police.

Joe spoke up. âThere are four or five in the gang working with Chris, and others offshore. Chris delivers smuggled diamonds. His pals in the caveâone tall and dark, one red-haired, and one shortâmentioned that he had diamonds in his brief case. Chris thought we had seen them when the case burst open. Gross saw a chance to kidnap one of us to keep us from talking.â

âA stupid move,â Frank commented. âEven if we had seen the diamonds, we wouldnât have known theyâd been smuggled. What about Mr. Wrightâs secret radio? Did they talk about that?â

âIâm not sure,â Joe answered. âGross mentioned a secret gadget, but since they smuggle electronic equipment, it could be anything. Do we still have the transistor?â he asked.

âYes. But itâs my guess someone connected with the smugglers figured out we have the radio and thought it might be in our trunk. Do you know the names of any of the others in the gang?â

Joe shook his head. âIâm sure thereâs a big boss, but they never mentioned him. One man who came to the cave had a nasal voice. He sounded like one of those burglars at Mr. Wrightâs house.â

âAnd heâs afraid of someone named Shorty,â Frank added. âThis is a real clue.â After a moment he said thoughtfully, âSo weâre up against a gang of smugglers.â

âI think,â Aunt Gertrude said firmly, âthat you boys should leave well enough alone. Joe is back safe and sound, and we ought to be satisfied. If you try tracking down those smugglers, youâll only end up in trouble. Leave it to the police.â

The conversation was interrupted by the ringing of the telephone. Frank answered the call.

âAre you one of the Hardy boys?â a strange voice asked.

âYes. Who is this?â

âThe inventor of the secret radio.â

âWhatâs your name?â Frank asked.

âYou know I donât want to mention it on the phone. All I want to find out is whether you still have it,â the man replied.

Frank was suspicious at once. He beckoned his mother and wrote on the telephone pad, Go next door and try to have this call traced. Then call the police and give them Joeâs clues to the kidnappers.

Aloud Frank was saying, âWhy are you so interested, sir?â

â âCause Iâm the inventor and I want the radio back.â The stranger spoke sharply.

A long parley followed. Finally, when Frank was sure his mother had had time to call the police, he said, âSorry not to help you, sir, but youâll have to get your information from my father. He isnât here right this minute.â

âYour father!â the man shrieked. âWhy, you impudent young pup! Iâll be right over and youâll give me that radio or IâllâIâllââ

The caller hung up.

CHAPTER IX

Smugglerâs Trail

THE evening passed with no further word from the mysterious caller who had phoned from a public booth but had disappeared before the police could track him down. Frank and Joe discussed the situation.

âMaybe he was scared off,â Joe suggested. âAnd what about the secret radio? Someone may look in that trunk again.â

âRight,â Frank agreed. âIâll bring it in here. But each time we leave the house letâs take the invention along.â

Before the family went to bed, Mrs. Hardy turned on the burglar alarm, which was connected to every door and window in the house and garage. There was no disturbance during the night.

âWeâre safe so far,â Frank remarked at breakfast. âMaybe the police have caught Chris and the others. Iâll phone Chief Collig.â

âSorry, Frank,â came the report from headquarters. âNone of my men has picked up a clue.â

Almost a week passed. Still there was no news. The kidnapper-smugglers had covered their tracks well.

Joe had recovered from his experience and Frankâs injured leg had healed. The brothers were ready to continue their sleuthing. They asked Chet, Jerry, and Biff to help them.

âGross and the others may sneak back to Bayport,â Frank prophesied. âTheyâll get nervy soon and we may have a chance to trip them up.â

âWhere do we go from here?â Biff asked.

âA tour of the docks,â Frank answered, âto hunt for a whaler.â

A long but wary search of Bayportâs busy waterfront yielded nothing. Finally all the boys went home.

Frank and Joe found that Aunt Gertrude had been shopping. âWho is that new young man working in Bickfordâs jewelry shop?â she asked abruptly.

âI never saw a young man working in there,â Frank replied. âThe only clerk I know of is elderly and heâs in the hospital right now.â

âA young man, I said,â Aunt Gertrude repeated in a tone that did not invite contradiction. âA very suspicious-looking young man. He wasnât there the last time I went in.â

âHeâs new to me,â Joe remarked. âWhat happened?â

âYou see this diamond pin Iâm wearing?â Aunt Gertrude pointed to a small one on the shoulder of her dress. âWell, this clerk kept eying it while I was looking at some inexpensive watches.â

âHe was probably just admiring it, Aunty,â Frank suggested.

âAdmiring it, yes. With the thought of stealing it!â Aunt Gertrude was warming to her subject. âYou canât fool me about young men. Besides, Iâve seen that clerk somewhere before.â

âWhere?â Joe asked.

âIâm not sure, but I know I saw him.â

âIs that all you have against the poor fellow?â Frank asked jokingly.

âItâs enough. Mark my words, that young jewelry clerk is bad. Next thing we hear of him heâll be in the penitentiary for robbing his employer!â

This dire prediction left the Hardy boys wondering. Aunt Gertrudeâs intuition was amazing. They would drop into Bickfordâs tomorrow and talk to the clerk.

The following morning the boys decided to walk downtown. They made sure their mother and aunt would be at home to guard Mr. Wrightâs invention.

On the way Frank said, âI wonder why those smugglers operate in Bayport. Wouldnât you think theyâd pick one of the larger cities?â

âPerhaps they are known in those places,â Joe suggested. âI wish I could have heard more when I listened to them in the caveâlike where the diamonds and electronic stuff came from and where they make their headquarters.â

Suddenly Joe gripped his brotherâs arm. âLook!â he said tensely.

He gestured toward a man walking on the other side of the relatively deserted street and Frank almost shouted with excitement. The man was tall and muscular, with a shock of fair hair protruding from beneath his hat. He was the person who had been at the airportâthe one they now suspected might be part of the kidnap-smuggler gang.

âIâll bet his name is Chris!â Frank whispered.

âLetâs trail him and see where heâs going.â

âWeâd better cross the street. He may catch sight of us.â

Excitedly the Hardys hurried to the opposite side and fell in behind the fair-haired man. âChris,â apparently unaware that he was being followed, strode along at a rapid gait.

âPerhaps heâs going to meet some of his pals,â Joe said.

âWe wonât let him out of our sight,â Frank said, âand if we meet a policeman Iâll ask him to notify headquarters.â

They were careful to remain far enough behind so that there were always several people between them and their quarry. The fair-haired man did not look back. He seemed to be in a hurry.

âYouâd think Bayport has no cops,â Joe complained when the boys had gone several blocks without meeting one.

The Hardys trailed the big man for several blocks. Abruptly he struck off down a side street. The boys had to run in order to keep him in sight.

âPerhaps,â Joe said, âhe saw you and me and is trying to shake us.â

âI donât think so. I believe heâs going to the railroad station.â

âGood night! If he takes a train out of town, weâll lose him.â

âI donât intend to lose him,â Frank declared. âHow much money do you have with you?â

Joe groped in his pockets. âAbout seven dollars.â

âLuckâs with us. I have thirty. We can take the train if he does, but I hope he wonât go far.â

It was soon evident that Chris was indeed bound for the station. When he came in sight of the big brick building, he broke into a run and disappeared through the massive doorway.

The Hardys hastened in pursuit, still looking for a policeman. Just before reaching the station, they saw one of their fatherâs friends. Quickly Frank told him the story and added, âCall headquarters and my mother.â He dashed after Joe.

When the boys entered the station they saw Chris just leaving one of the ticket windows. He ran across to an exit, raced through it, and darted toward a waiting train.

Frank stepped up to the window which the fair-haired man had just left.

âWhere to?â the agent asked.

âWe wanted to meet a man here,â Frank explained. âHeâs a big fellow with blond hair. Have you seen him?â

âJust bought a ticket to New York City a minute ago.â

Frank was taken aback. He had not anticipated that Chris would be going as far as New York. However, having once picked up the trail, the young detective decided to follow it.

âTwo one-way tickets,â he said.

âYouâll have to hurry,â the agent said. âThe express is due to leave right away.â

Frank grabbed the tickets. He heard a whistle and saw that the train was beginning to move.

The boys dashed to the platform. Joe, in the lead, scrambled up the rear steps of the last coach. Frank followed.

When the boys had recovered their breath, they went through to the coach Chris occupied. They halted in the rear doorway and made a quick survey of the occupants.

Alone in a front seat they saw a familiar thatch of yellow hair. Chris was unaware that he had been followed.

The boys took seats at the rear of the car, and settled down for the journey.

CHAPTER X

Elevator Chase

âI hope the Bayport police communicate with the authorities in New York,â Frank remarked. âIf they meet the train and arrest Chris, our worries will be over.â

âAnd if they donât?â Joe asked.

Frank gave a wan smile. âOur troubles will just be starting. Thereâll be crowds and itâll be tough to keep track of him.â

The train did not make many stops, but each time it did, Frank and Joe were ready to hop off in case Chris should alight. At length the train reached the suburbs, clattering past miles of factories and houses, and finally lurched to a halt in the underground station in New York City.

The boys watched Chris intently as the passengers prepared to leave. The fair-haired man did not look back once. He put on his hat and strolled toward the front of the car.

âWeâll get out at the back and keep an eye on him from there,â Frank said.

The Hardys scrambled onto the platform where passengers were just beginning to file up the ramp to the waiting room. Chris had not yet appeared, so the brothers, shielding their faces, made their way quickly to the exit gate.

âI donât see any police,â Frank remarked, disappointed.

âNo,â Joe replied. âI guess weâll have to take over.â

The boys emerged into the concourse. There, in the enormous, high-vaulted station, booming with hollow echoes, they waited for Chris to appear.

He stalked through the gate, looking neither to right nor left. The boys quickly fell in behind him. He towered above the throng, and they had little difficulty following him. Despite the crowds that jostled them, the Hardys managed to keep Chris in view and pursued him out into the street.

âWhatâll we do if he hops into a taxi?â Joe asked.

âHop into one ourselves and hope we can trail him,â Frank said.

âIâd feel better if we had more money with us,â Joe mumbled.

The man they were trailing still seemed unaware that he was being followed.

âItâs going to be mighty hard for one taxi to follow another in this traffic,â Frank remarked.

âMaybe we wonât need one,â his brother suggested. âAnyhow, these New York taxi drivers are pretty clever. I think if we tell one to follow a car we point out and make it worth his while, he could do it.â

âGoing to cost a lot of moolah,â Frank said.

They were relieved when their quarry continued walking.

âCome on!â Frank called.

The two sleuths had a twofold problem: to follow Chris and be careful he did not suspect they were after him. Twice he swung around while they hurried along the crowded sidewalk, and it seemed as if he were suspicious.

On these occasions the boys dodged back of passers-by. After two momentary surveys, Chris hastened on again.

âI donât believe he saw us,â Frank murmured as they again took up the chase.

âNo, evidently not. But weâre coming to heavy congestion. Look at the crowd and there are traffic signals. If he gets across the street ahead of us and you and I are held up by a red light, weâll lose him.â

The boys were anxious as they approached a busy corner where a policeman was directing the flow of automobiles and pedestrians.

âShall we ask his help?â Joe asked.

âI doubt he could leave his post,â Frank answered.

Just what Joe had feared took place. Chris was among the last to slip across the thoroughfare before the lights flashed from green to red and the officer blew his whistle sharply. Joe groaned.

âJust our luck!â he cried.

âLook!â Frank exclaimed. âWeâre in luck!â

Chris was speaking to a man on the other side of the street. Evidently the stranger had asked directions and Chris had halted to explain and point out the location of a certain street. He took such pains with the man that by the time he finished, the traffic light had again flashed green.

âLetâs go!â Joe cried.

They trailed Chris along the street for several blocks, then he turned into a large office building. Inside was a row of elevators opposite the entrance. Frank and Joe hesitated a few seconds about following Chris.

âCome on!â Joe urged. âIf he gets in an elevator, and we arenât there, we wonât know what office heâs going to.â

âYouâre right!â Frank agreed.

They hurried into the lobby just as Chris stepped into one of the cars. The door closed and he shot upward. Fortunately he was the only passenger and the boys watched the dial. The car stopped at the tenth floor.

âI hope he doesnât get away,â Joe murmured excitedly.

âWe never would have dared get into the same elevator with him,â Frank said. âHeâd have recognized us.â

The boys stepped into the next car. It soon filled and shot up leaving passengers off at various floors. The boys left it at the tenth. Each wondered if they could locate Chris in the maze of offices.

Again luck was with them. As Frank and Joe looked down a corridor, Chris was just entering an office. Evidently he had been delayed looking for his destination.

The Hardys hurried to the door as it closed behind the suspect. It was a green-painted steel door with an open transom. The sign read:

SOUTH AFRICAN IMPORTING COMPANY WHOLESALE ONLY

âI wonder what heâs doing in there,â Joe murmured.

Frank put a finger to his lips. The sound of muffled voices could be heard from the office. Apparently Chris and the others inside were so far from the door that their conversation was indistinct.

A moment later Chrisâs voice came loud and clear. He must be walking toward the outer door!

âWeâd better scram,â Frank advised.

âWhen he comes out, shall we grab him?â Joe asked.

Frank shook his head. âIf those are buddies of his in there, they may grab us.â

The boys scooted up the corridor and watched Chris over their shoulders. He did not notice Frank and Joe. The suspect was looking intently at some papers in his hand as he went to the elevators and pushed a button for an ascending car. He was going to a higher floor

âShall we follow him?â Joe whispered.

âToo risky. Letâs go down and wait in the lobby, then take up the trail again.â

After Chris had gone up, the boys took a Down car. On the ground floor they watched each descending elevator. After half an hour had passed, their patience was rewarded. Amid a carload of businessmen, they saw the burly form of the big blond man towering above all the others.

âCome on!â Frank whispered to Joe as Chris moved toward the street doors.

Again the chase was resumed in the crowded street. For several blocks Chris maintained a straight course. Then he swung around a corner and stalked down a side street. The sleuths hurried after their quarry and saw him dip beneath a restaurant sign below street level.

âOhâoh!â Joe muttered. âIf we follow him in there, he canât miss us.â

âLetâs see if there are many customers inside,â Frank suggested. âIf so, we just might be able to get away with it. Could be heâs meeting someone there.â

Frank went down the steps leading to the restaurant and made a quick survey of the place through the door. It was almost full.

âChris is taking a table in the rear, and heâs not facing the door. Come on, Joe! Weâre not letting him out of our sight.â

Boldly Frank and Joe entered the place. It was a cheap restaurant, with a row of booths along one side. The boys slipped quickly into one of the compartments. They could watch Chris but he could not see them.

âThis is a break!â Joe whispered.

An untidy-looking waiter came over and they gave their orders. After he had gone to the kitchen, the boys put their money on the table.

âThereâs enough to pay for a hotel room if we have to stay over, and a few more meals.â

âWe canât afford to hang around New York long,â Joe remarked, eying their available cash. âI guess weâd better tell the police about Chris and forget trying to spot his buddies.â

Suddenly Frank sat bolt upright. âChris is getting up from his table.â

âLeaping lizards!â Joe exclaimed. âHeâs heading right for us!â

CHAPTER XI

Discovered !

JOE pretended to be searching for something he had dropped and quickly ducked his head underneath the table as the fair-haired man approached. Frank snatched up a menu and held it in front of his face.

There was a tense moment as Chris drew nearer. To the boysâ relief, he brushed past without noticing them and walked directly to the cashierâs counter. The Hardys got ready to pursue him, but he only stopped to glance at a newspaper lying there, then returned to his own table.

âWhew, that was close!â Joe murmured as he raised his head.

âIt sure was,â Frank agreed. âBut we have one thing in our favor. Weâre the last persons in the world Chris would expect to find trailing him in New York City.â

The Hardys watched as a waiter walked up to the big manâs table. Apparently Chris was well known in the restaurant, for the two exchanged a few words laughing all the while. Presently a slim, sharp-featured man emerged from a door to the kitchen and went directly to Chris. He sat down, then began to talk.

âI think,â Joe whispered, âitâs time for some action. How about my going outside and looking for a policeman?â

âGood idea, Joe. I have a feeling the man with Chris should be investigated, too. He may be one of the smugglers.â

Joe slid from the booth and went outside. No officer was in sight, but there was a public-telephone booth nearby. âIâll call headquarters from here,â Joe decided and dialed the number.

He was connected with a lieutenant, who said they had been alerted by Chief Collig, but the boysâ message to him had been delayed, and the call to New York had come too late for the police to meet the train from Bayport. âI will send two officers to the restaurant. If this man Chris hasnât started to eat yet, heâll be there a while. By the way, we got a message that you are to phone your home at once.â

âThank you,â said Joe and hung up.

He immediately dialed the Hardy house. Aunt Gertrude answered. âMy, you boys certainly take off fast! You ought to be right here taking care of the secret radio mystery.â

âWhat do you mean, Aunty?â

âI mean that I canât understand your father. He sent a telegram saying, âInventor will phone. Do as directed.â Well, the inventor called and said we should leave the radio on the front steps at ten oâclock tonight.â

Joe was astounded. After a momentâs thought he said, âI think the telegram was a hoax. Dad would never do such a thing. Somebody may be listening in on this call, but Iâll take a chance. Put a package on the steps but not the radio. Then ask the police to shadow the house and pick up this fake inventor. I have to say good-by now. Frank and I have one of the gang almost nabbed. Give my love to Mother. Tell her weâre sorry we couldnât call before this.â

Joe returned to the restaurant and in whispers repeated his whole conversation. Frank nodded, then pointed to Chrisâs table.

âI heard that thin guy call him Chris, so we know for sure weâre on the right track.â

The smuggler and his companion were busily engaged with pencil and paper. Chris seemed to be explaining something that did not please the other man, for he shook his head doubtfully and crossed out what Chris had already jotted down.

âIâd give anything to know what those two are talking about,â Frank said in a low tone.

âSo would I,â Joe replied and started to eat.

At that instant the boysâ attention was diverted to a stocky man who had just entered the restaurant. He glanced in their direction, then made his way toward them. He planted himself in front of their table and glared at the Hardys.

âWhatâs the idea of sittinâ at my table?â he demanded.

âYour table?â Frank asked in surprise.

âYes. This is my table youâre sittinâ at. Youâd better clear out!â

âThere are lots of other tables,â Frank retorted in a low voice.

âSure. And you can have any one of âem you want.â

Frank decided that nothing would be gained by arguing with the stranger. Both boys returned quietly to their meal and did not look up.

âWell,â the man roared, âare you gonna move?â

âAs soon as weâve finished our lunch,â Joe snapped.

âYouâll move now! This is my table youâre sittinâ at, and I mean to have it!â

The young sleuths were infuriated by the intrusion. Unknowingly the man was putting them in a difficult position. If they stood up to walk to another table, Chris would surely spot them and might escape before the police arrived! If they remained where they were, they probably would be discovered, since the incident was beginning to attract attention.

Frank signaled a waiter standing nearby.

âWhatâs the trouble, Mr. Melvin?â he asked.

âThese kids are sittinâ at my table,â Melvin protested. âMakeâem move!â

The waiter looked uneasy. âI canât ask these young men to move, Mr. Melvin. They were here first.â

âAinâtIagood customer of this restaurant?â

âYes, indeed. But there are plenty of other tables, sir. If you donât mindââ

âI do mind. These boys can get outta here or I wonât come back to this restaurant again!â Melvin shouted.

Frank saw that Chris and his friend had turned and were looking in the Hardysâ direction. At once Chris spoke to the sharp-featured man, who nodded. Then both darted toward the kitchen door and disappeared through it.

Joe said to the waiter, âWeâre not afraid of this fellow, but weâll leave just to save trouble.â

The boys got up. Melvin, breathing defiance and declaring that no person could sit at his table and get away with it, promptly sat down in the seat Frank had just vacated.

Joe dashed to the back of the restaurant and whirled into the kitchen. Chris and his friend were not in sight, but a back door was open and Joe assumed the men had ducked outside and up a delivery alley to the street. He hurried back into the restaurant.

Frank had hastened to the cashierâs desk and paid the boysâ check. Then he ran up the front steps and into the street. The police had not arrived.

Joe joined his brother. âChris left by the back door,â he said. âHe should be coming up that alley.â When the two men did not put in an appearance, he added, âYou stay here, Frank. Iâll run down.â

Joe returned in a short time. âCome on!â he cried, and explained that the alley joined another one that led to the busy street beyond. They followed it to the sidewalk, which was teeming with pedestrians. Chris was not in sight.

âWeâve really lost him this time,â Joe commented in disgust.

âI have an idea,â Frank said. âLetâs walk along this street in opposite directions for about ten or twelve blocks. Iâll head downtown, you uptown. Thereâs a slight chance one of us might spot Chris.â

âBut he might have gone cross town,â Joe argued.

âYouâre right. But what have we to lose?â

âOkay, Frank, Iâm game. But thereâs just one hitch. If I should see Chris, how do I let you know and vice versa?â

Frank looked around and pointed to a public-telephone booth. He walked over and jotted down the number.

Rejoining his brother, he said, âWeâll meet back here in half an hour. However, if one of us gets back and the other isnât here, I say stay by the phone and wait for a call.â He handed Joe a copy of the number and took one himself.

âHereâs hoping!â Joe declared with a grin as the boys went their separate ways.

Frank walked along slowly, dividing his attention between weaving among pedestrians and searching for his quarry. When he had covered nearly fifteen blocks, Frank decided to work his way back on the opposite side of the street.

He stopped for a moment at an amusement arcade to watch the people playing the various coin-operated machines.

As Frank was about to continue walking, his eyes widened in surprise. Toward the rear of the arcade a big fair-haired man was engaged in conversation with three ominous-looking characters. Frank carefully edged his way inside the arcade for a better look. He was certain now.

The man was Chris!

CHAPTER XII

Tunnel Scare

FRANK mingled with the crowd in the arcade and cautiously worked his way toward the spot where Chris and his companions were standing. He kept glancing toward the street, hoping a policeman would come along. Soon the young sleuth was close enough to overhear the menâs conversation.

âSounds like you got in with a gang thatâs going places,â declared one of Chrisâs companions. âHow about talkinâ to your boss and gettinâ us in on the action?â

âSorry, but I canât help you guys,â the fair-haired man answered. âThe big boss has all the men he needs.â

âKeep us in mind if anything comes up,â one of the trio chimed in.

Just then a man who had been playing one of the game machines alongside Frank shouted, âWhee! Iâve won ten in a row. I musta broke some kind oâ record!â

The outburst caused Chris and his friends to look in the manâs directionâand therefore right at Frank. The boy turned quickly and gazed into one of the coin-operated machines. In its highly polished surface he could see Chrisâs reflection.

âHe must have recognized me!â Frank thought, noting a look of surprise on the smugglerâs face.

Frank watched while the fair-haired man whispered something to his friends, then turned to go back to the street.

Determined not to let the big man out of his sight, and to contact the first police officer he met, the young detective started off in pursuit. To his dismay, he was intercepted at the entrance by Chrisâs three companions.

âWhere dâyou think youâre goinâ, kid?â one of them growled.

Another said, âWe donât like the idea of our pal being shadowed.â

âGet out of my way!â Frank demanded.

One man stepped behind the youth. The other two each grabbed an arm and led him out of the arcade.

âWeâre goinâ for a little walk,â one of them snarled, âand if you make one sound, itâll be curtains for you!â

Frank was forced to walk about half a block, then he was led into a dark, narrow alley.

âYou need to be taught a lesson, kid,â the man behind Frank said. âWe donât like snoopers.â

Frank was in a desperate situation, but he did not panic. With catlike speed he thrust out his leg and tripped the man on his right, then flung him down so hard the grasp on the youthâs right arm was broken. With his free arm Frank jabbed an elbow into the midriff of the man behind him.

âOuch!â his opponent grunted loudly.

The third man, who still had a firm grip on Frankâs left arm, was unable to dodge the boyâs blow. It caught him on the chin and he crumpled to the ground.

Frank had only a second to collect his wits. One of his stunned opponents had recovered quickly, scrambled to his feet, and lunged at him. Just as Frank dealt the man a staggering blow, he heard a noise behind him. Before Frank could turn, he was struck on the head with a hard object.

Several minutes passed before Frank regained consciousness. He slowly got to his feet and looked around. The three men were gone. Frank grimaced as he felt a large swelling on the back of his head. Then he noticed that his wrist watch and wallet were missing.

âChris has some rough playmates,â he thought. âAnd theyâre petty thieves to boot.â

Still a bit unsteady on his legs, Frank finally started uptown to rendezvous with his brother. Frankâs body ached, but a light rain which was falling seemed cool and refreshing to him.

When Joe saw Frankâs condition, he exclaimed, âLeaping hyenas! You look as if yuuâd fallen into a cement mixer!â

âNot quite,â Frank replied. âI ran into some of Chrisâs pals.â

âWhat! You mean you caught up with the smuggler?â

âYes, but lost him again. Iâll tell you all about it later. But first letâs find some shelter from this rain. Iâm cold.â

They ducked into a doorway. Frank straightened his tie and brushed off his clothes in an effort to look more presentable.

âMy wallet was stolen,â he said. âHow much money do you have left?â

Joe dug into his pockets. âExactly six dollars and thirty-seven cents.â

âIâm starved,â Frank announced. âAnd weâll need most of that to get a good meal. Anyway, itâs not enough for our fare back home. Letâs find a restaurant and a phone. We can call Mother collect and let her know what has happened so far. Hope she can wire us some money.â

The rain lessened and the boys hurried along the street in search of an eating place. They examined the menus posted in the windows of several restaurants, hoping to find one that would not exceed their budget.

âHereâs a possibility,â Joe said. âThe menu looks good and the prices are reasonable.â

The boys entered the restaurant and sat down. Shortly a waiter walked over to them. He eyed Frankâs rumpled clothes and the manâs manner became abrupt. The Hardys had already selected a dinner listed on the window menu and ordered immediately.

âI have a feeling heâs in a hurry to get rid of us.â Joe grinned as the waiter walked off.

âDid you see the way he stared at me when he came over?â Frank laughed. âI admit I look a little shabby. He probably thinks weâre not going to pay our bill.â

After finishing dessert, Frank rose. âGive me some change and Iâll place a call home,â he told Joe. âMeanwhile, you take care of the check.â

Locating a phone booth at the rear of the restaurant, the young detective deposited the coin and dialed the operator.

âIâm sorry,â said a feminine voice when Frank tried to make a collect call to Bayport. âViolent storms up there have temporarily affected the service. I suggest you try again in about an hour.â

Disappointed, Frank returned to the table. To his surprise, Joe was involved in an argument with their waiter.

âWhatâs wrong?â Frank asked.

âThere seems to be a misunderstanding about our check,â Joe declared. âItâs almost double the amount listed on the menu we saw in the window.â

âI already told you,â the waiter growled. âThose prices are good only up to three oâclock. After that, you pay more.â

âIâll say you do,â Joe retorted. âBut how were we supposed to know?â

The waiter picked up a copy of the menu the boys had seen in the window and thrust it at them âCanât you read?â He pointed to a line of fine print at the bottom of the menu:

THIS MANAGEMENT RESERVES THE PRIVILEGE TO CHANGE LISTED MENU PRICES AFTER THREE P.M.

âWow! You almost need a magnifying glass to read it!â Joe snapped.

âDonât try to squirm out of this,â the waiter said harshly. âI had you kids sized up the minute you walked in here. Iâm going to get the manager!â

The waiter reappeared shortly with a short, stocky man wearing a dark suit and a bow tie.

âI hear you boys canât pay your check,â he said.

Joe started to explain. âWe can pay you half of it now and ...â

âWe donât sell meals on the installment plan,â the manager stated tersely.

âGive us a little time,â Frank pleaded. âJust as soon as we can get a call through to our home, weâll have some money wired.â

âA lot of good that will do me,â the manager answered. Suddenly his expression changed. His face broke into a wide grin. âTell you what! Iâm in need of a couple of dishwashers right now. Each of you work for three hours and Iâll call it square. You keep your money.â

The Hardys were reluctant, but being short on funds, with no place to go, and unable to get through to Mrs. Hardy yet, they agreed.

After working a while Joe said in disgust, âA couple of private detectives end up in New York as kitchen police!â

âI wouldnât complain too much,â Frank said, grinning. âWhat if we had to wash these dishes by hand!â

âWhy do we have to do them at all?â Joe complained. âDad has several friends here in the city. Theyâd be willing to help us out with some money.â

âI know! But I think we should go to them only as a last resort.â

Frank waited nearly four hours before getting a call through to Bayport. Finally the lines were repaired, and a long-distance operator connected him with Mrs. Hardy.

âYour Aunt Gertrude and I have been worried sick about you and Joe,â she said. âThereâs been a bad storm here. Where are you?â

âStill in New York. But guess what? Joe and I are washing dishes to pay for our dinner.â

Mrs. Hardy laughed and promised to wire them money right away.

âSend it to the telegraph office at Grand Central Terminal,â Frank requested. âAnd donât worry about us. Weâre fine, and weâll probably be home tomorrow. Now tell me, did that fake inventor show up?â

âNo. I guess the storm was too bad. The detectives stationed here were needed elsewhere and had to leave. The box on the steps is soaked. We turned the lights off and have been watching from the window. Maybe we can catch a glimpse of whoever comes.â

âGood. âBye now. I hope nobody tapped this call.â

When Frank and Joe finished their work, they hurried from the restaurant. It was still raining when they stepped onto the street. âItâs almost midnight. What now?â Joe asked.

âLetâs take the subway to Times Square,â Frank said. âThen we can get the cross-town shuttle to Grand Central. At least we can keep dry there until our money arrives.â

There were only a few people waiting for the shuttle train when the boys arrived at Times Square. Several minutes passed, then suddenly Frank clutched his brotherâs arm.

âWhatâs the matter?â Joe asked.

âThat man behind the post!â Frank whispered. âHeâs one of Chrisâs friends!â

Just as Joe glanced up, the man brushed against one of the strolling passengers on the platform. The young detectivesâ keen eyes saw him lift a wallet from his victimâs pocket.

âHey! You!â Frank shouted, rushing toward the pickpocket with Joe close behind him.

Startled at Frankâs outcry, the thief quickly removed the money and dropped the wallet. He leaped off the platform onto the tracks and disappeared into the dark tunnel. The boys took off in pursuit.

âWatch that side rail!â Frank warned his brother. âItâs charged with high-voltage electricity!â

The young detectives had run a considerable distance into the yawning tunnel when they halted abruptly.

âWhatâs that rumbling noise?â Joe asked.

âItâs the shuttle train!â Frank screamed. âAnd itâs coming our way!â

Seconds later the fast-moving train loomed from around the bend. Would the Hardys escape in time?

CHAPTER XIII

Exciting Assignment

âRUN for it!â Joe yelled.

The boys whirled and dashed through the tunnel. As the train rapidly gained on them, its headlight illuminated the walls. Stretching along one side was a power line encased in metal piping. Frank spotted it.

âThatâs a conduit line!â he shouted. âGrab it and flatten yourself against the wall!â

They made a desperate leap, caught hold of the narrow piping, and stiffened themselves hard against the wall. Seconds later the train sped past them. The roar was deafening and the mass of air that was pulled along lashed the Hardys like a gale. The sides of the cars were barely inches away as the lighted windows passed by in a blur.

Soon the last car disappeared around a bend. The youths jumped onto the tracks and made their way back to the Times Square station plat form. Both were trembling.

âWhat do you think happened to the man we were chasing?â Joe asked finally.

âProbably heâs used this tunnel before as a means of escape,â Frank replied, âand knows the layout well. Iâm sure heâs heading for Grand Central station.â

Arriving at the platform, the boys spotted the man Chrisâs pal had tried to rob. He was talking to a police officer.

âThese are the two boys who chased the pickpocket into the tunnel,â the man told the policeman as the brothers walked toward them.

The officer turned to Frank and Joe. âThis man claims someone stole his wallet.â

âThatâs right,â Frank said, âand heâs probably the same one who lifted mine this afternoon. We chased him but he got away.â

âBy now he has no doubt reached Grand Central,â Joe added.

âIâve alerted a couple of the men on duty there,â the policeman said. âTheyâll be on the lookout for him.â He stared at the boys curiously. âSay, that was a risky job for you fellows to take on!â

The boys introduced themselves to the officer and showed him their credentials.

âSo youâre the Hardys,â the policeman remarked.

âIâm Reilly. Your fatherâs name is something of a legend around the department.â

âDad is a great detective,â Joe said proudly.

At the officerâs request, the boys gave him a description of the pickpocket. Reilly then took the name and address of the man who had been robbed.

Shortly the next train arrived and the Hardys stepped aboard. When they got off at Grand Central station, Frank and Joe noticed a commotion at the far end of the platform. A group of spectators had assembled.

âLetâs see whatâs going on,â Frank suggested.

As the boys walked forward, Joeâs eyes widened. âHey, look!â he yelled. âThereâs the pickpocket we chased!â

âHeâs being questioned by two policemen,â Frank observed. âThat was quick work. They mustâve nabbed him coming out of the tunnel.â

The boys pressed their way among the spectators.

âI ainât done nothinâ,â they heard the pickpocket snarl.

âThatâs not true!â Joe declared. âHe tried to steal a manâs wallet. My brother and I saw the whole thing!â

âAnd I suspect he took mine and is a pal of some smugglers,â Frank added.

âWho are you?â one of the policemen asked.

The boys identified themselves once more, then related the incident at the Times Square station.

One of the officers nodded. âWe were alerted to be on the lookout for this guy.â

âWe know all about him,â the second policeman said. âHis name is Torchy Murks. Has two convictions for petty larceny. We had reports of a pickpocket that looks like him working the subways recently.â

âYouâre crazy!â Murks growled. âIâm being railroaded!â

âWeâll see about that.â

The officers requested the boys to accompany them. At the precinct Murks was marched off to the interrogation room.

A few minutes later a tall, muscular, square-jawed man emerged from the squad room. He walked directly to the Hardys and extended his hand in greeting.

âOne of the officers just told me youâre the sons of Fenton Hardy,â he said.

âThatâs right.â

âItâs a pleasure to meet you. Iâm Detective Lieutenant Danson. I joined the force as a rookie just before your father left the department. A great detective. Come into my office.â

The youths were ushered into a small but comfortable office, where Danson offered them chairs and seated himself behind his desk.

âI hear you fellows had a scrap with Torchy Murks,â he said. âSlippery character. Well, tell me, what brings the famous Hardys to New York City?â

The boys related their experiences of the past two weeks, ending with an account of how they had trailed the smuggler-kidnapper Chris to New York.

Lieutenant Danson sat thoughtful for several moments. âThatâs strange,â he mumbled to himself.

âWhat is?â Joe inquired curiously.

âIt might be just a coincidence,â Danson muttered. âThen again ...â

The boys watched with interest as the lieutenant thumbed through his private list of telephone numbers. âAn FBI agent I know, named Emery Keith, dropped into my office a couple of days ago and told me about two suspects his office wants for questioning. From his description of the men, one of them sounds like this big blond fellow Chris. Of course our men have been on the lookout, but Iâd like Keith to hear your story.â

Twenty minutes later two neatly dressed men arrived at the lieutenantâs office.

âIâm Agent Keith,â the tall, light-haired one said to the Hardys. Then he introduced his shorter, dark-haired companion. âAnd this is my assistant, George Mallett. Iâve heard a lot about your father. Some of our agents have worked with him.â

After the formalities, they all sat down to discuss the case. Frank and Joe told their story about the kidnapping and smuggling.

âHmm!â Keith muttered. âInteresting lead!â The agent eyed the Hardys for a moment before speaking again. âDoes the name Taffy Marr ring a bell with you fellows?â he asked.

âIâm afraid not,â Frank replied.

âTaffy Marr,â Keith said, âis one of the slickest crooks in the country. Heâs the leader of the smuggling ring and I suspect is the boss of Shorty, Chris, and their pals. Marr is youngâthe innocent-looking typeâbut as clever and cold-blooded a crook as youâll ever come up against.â

âWhat else can you tell us about his looks?â Frank asked.

âNot much. Taffy is slender, of average height, and uses a lot of disguises, so weâre not exactly sure what he does look like. One of our men did spot a triangular scar on Marrâs left forearm. No doubt heâs self-conscious about this identification and he usually wears long sleeves.

âTaffy came from the West Coast a few months ago and organized a gang,â Keith went on. âThe groupâs been flooding the country with smuggled diamonds. Itâs so bad that the Jewelers Association is offering a sizable reward to anyone who can trip up Marr. As for me, Iâd give a yearâs salary to put him in prison.â

Joe volunteered the information that the gang also smuggled electronic equipment, and added, âHave you any leads on Marrâs whereabouts?â

âThe last report shows he was here in New York,â the agent answered. âBefore that, it was Florida, then Virginia, Connecticut, New Jersey, and the Carolinas.â

âHe certainly gets around,â Frank commented.

âApparently heâs confining his operations now to the East Coast,â Keith said. âBut the problem is where. He has dropped out of sight completely.â

âHow long do you two plan to be in New York?â Keith asked the Hardys.

âNot much longer,â Joe said. We called home for money, and it should be at the Grand Central telegraph office by now. We plan to take the first train back to Bayport.â

âTell you what,â Keith said. âWhy not let us put you up at a hotel tonight at our expense? Then you can catch the morning train. Iâd like to have breakfast with you fellows and discuss the possibility of your working with us. But Iâll have to talk with my chief first.â

Frank and Joe were excited at this prospect and quickly consented. Lieutenant Danson drove them to Grand Central, where they found their money waiting, then they went to a nearby hotel. Completely exhausted, Frank and Joe were sound asleep within minutes.

Early the next morning they met Keith in the hotel restaurant and enjoyed a breakfast of sausage, wheat cakes, and fruit. Then the agent reviewed the facts on Marr and his gang.

âI realize our information is sketchy,â the agent said. âBut youâve given us some good leads and maybe you can dig up a few more.â

âWeâll certainly try,â Frank said.

âIâd like you fellows to be on the lookout for Marr in the Bayport area. The same goes for Chris. He may turn up there againâperhaps to meet Marr, if theyâre in the same racket.â

âYou can count on us!â Joe said eagerly.

Keith reached into his pocket and took out a small business card. On the back he jotted down a series of digits.

âI suggest you memorize this telephone number,â he said. âYouâll be able to get in touch with me or my assistant Mallett at any time.â

âRight!â The Hardys repeated the digits several times until both were sure they would not forget them.

Frank telephoned to check the trains and learned that one would depart for Bayport within half an hour. Keith drove them to the station and shook hands.

âGood luck, and good hunting,â he said with a smile. âI can assure you that the entire Bureau will be grateful for whatever help you can give it.â

When the boys arrived home, Joe jokingly stuck out his chest and said to Mrs. Hardy and Aunt Gertrude, âMeet a couple of Federal men!â

âWhatever do you mean?â his mother asked.

Frank told of Keithâs request and the women smiled. âItâs a big assignment,â Mrs. Hardy remarked, and Aunt Gertrude added, âYouâd better watch your step. This Marr fellow sounds pretty dangerous for you to tackle.â

âNow tell us,â Joe requested, changing the subject, âabout that fake inventor. Did the mysterious caller ever come for the box with the secret radio in it?â

âYes,â their mother replied.

âWas he caught?â Frank asked eagerly.

CHAPTER XIV

Identification Diamond

AUNT Gertrude answered Frankâs question. âOf course that crook was caught. The police came back and nabbed him. Inventor, nothing.â

âHurrah!â Joe shouted. âWho is he?â

âHe wonât talk and he had no identification on him. But Iâll bet he belongs to Chrisâs gang,â Miss Hardy said.

âYouâre probably right,â Frank agreed. âAnd they may all belong to Marrâs racket.â After a few momentsâ thought, he added, âI think I know a way to find out.â

âHow?â Joe asked.

Frank grinned. âIâll pretend Iâm a fellow gang member and go talk to him.â

The young detective telephoned Chief Collig, who gave his consent to the plan.

âWhat can you tell me about this man?â Frank asked.

Hearing that the prisoner was very short and strong, Frank instantly thought of the man the burglars at the Wright home had mentioned.

âSounds like Shorty,â he said. After hanging up, he asked Mrs. Hardy, âHave you an unmounted diamond?â

âYes. One that fell out of a ring. Why?â

âIâd like to borrow one as a sort of identification with the gang.â

âSwell idea,â said Joe. âIâll help you get fixed up.â The boys went upstairs and rummaged through their fatherâs supply of disguises.

When Frank emerged from the house, his best friends would not have recognized him. He wore a long cut wig and beard, tight-fitting slacks, and a turtleneck sweater. He roared off on his motorry cle, and on purpose went past the cell block.

As prearranged Chief Collig met him at the entrance to headquarters and escorted Frank to the prisoner, who looked idly through the bars.

âFriend of yours to see you,â said the chief. âMaybe he can persuade you to unbutton your lips.â

Frank gazed through the bars. âLike nuttinâ I will,â he whispered to the prisoner in a tough voice as soon as Collig had moved off. âHi, Shorty! Iâm sorry the dicks got yuh. But yuh didnât tell âem nuttinâ, did yuh?â

âNaw.â

Frank was jubilant. He had scored one point The manâs nickname was Shorty.

âDid yuh hear my new motorcycle?â he asked.

âYeah, I heard it,â Shorty answered. âWhad daya pay for it with?â

Frank pulled the diamond from his pocket. âWith some oâ dese.â

Shorty seemed impressed. âSay, whatâs yer name?â

Frank assumed an air of annoyance. âAinât Taffy told yuh âbout me yet?â

âNaw.â

The young sleuthâs heart was thumping with excitement as he said, âNameâs Youngster. I got a bonus on the last haul. Just joined up with Marr-when smacko!âI run into the toughest setup.â

Shorty, apparently convinced by Frankâs story, said, âI was lookinâ fer some chips, too. But Marrâll probably have me rubbed out for gettinâ in here.â

âDid the dicks take the Hardysâ package from yuh?â Frank asked.

âYeah. Before I could open it.â

âHowâd yuh like me to lift it? I could do it easy,â Frank boasted.

âFrom the dicks?â Shorty asked, astonished.

âNaw. The Hardys. The chiefâll give it back to âem.â

Shortyâs thin lips broke into a smile. âThen Taffyâll think I didnât bungle after all?â His face clouded again, however. âLessen yuh double-cross me,â he added.

âNameâs Youngster,â Frank told the prisoner

âI wonât squeal,â Frank said. âIâll tell Marr yuh give it to me to deliver. Say, whereâs he holinâ up now? I seen him in New York anâ he told me to come here anâ wait till I heard from him.â

âGuess heâs still at Bickfordâs,â Shorty answered, and added with a smirk, âBest place to hide out with a wad oâ rocks.â

At that moment a voice called, âTimeâs up for visitors.â A guard came in Frankâs direction.

âOkay, but donât rush me,â the elated boy said in a tough voice.

He swaggered out of the police station and walked toward his motorcycle. What should he do now? Divulge the information to Collig at once and have the police pick up Taffy Marr?

âIâll call him, anyway,â Frank decided, âand he can notify Keith.â

Collig said he would stake plainclothesmen at the shop. âIâll let you know what happens.â

When Frank reached home, Aunt Gertrude met him at the door. âIâm glad youâve come,â she said excitedly. âWe must do something at once about that young clerk at Bickfordâs.â

âWe are going to,â her nephew assured her. âThat is, the police are.â

âWell, I can tell them something,â Aunt Gertrude said. âI was going to tell you what I remembered about him.â

âYou know something about him?â Frank asked.

âIâll say I do. You recall the tall, fair-haired man who bumped into me at the Gresham railroad station and called me an old whaler? Well, it suddenly came to me that one of the men he was talking to was the very same young man whoâs working at Bickfordâs!â

âWhat!â Frank exclaimed. âYouâre sure?â

âNow listen here,â his aunt said sharply. âWhen Iâm sure, Iâm sure.â

âAunty, this is great news!â Frank exclaimed.

Her announcement changed the whole scheme of attack. âDoes Joe know about this and where is he?â Frank asked.

âHe hasnât heard my story because I just remembered. Joe wentâHere he comes now.â

As Joe came in, he asked, âFrank, how did you make out?â

âGreat! Listen ! Taffy Marr is working at Bickfordâs!â

âNo kidding?â

âItâs straight. I got the tip from Shorty, the prisoner,â Frank answered. âAnd listen to this. Aunt Gertrude saw Marr with Chris in Gresham! While I remove my disguise, will you call Chief Collig and tell him this?â

âOkay, and letâs go down and watch the fun when Marr is arrested,â Joe urged.

It took Frank only five minutes to take off his costume and makeup. Since Mrs. Hardy and Aunt Gertrude planned to leave the house, Joe put Mr. Wrightâs invention in the tire well of the boysâ car. Then he and Frank rode downtown in the convertible. When they reached Bickfordâs, there was a good-sized crowd in front of the jewelry store.

âWhatâs going on?â Joe asked a bystander.

âDonât know. An attempted holdup, I guess. Police arrived and circled the building. Weâve been waiting for them to bring somebody out.â

A siren began to wail and seconds later an ambulance raced up the street. It stopped in front of the jewelry store. A hush fell over the crowd as they waited for the victim to be brought out. Would it be Taffy Marr, or a policeman who had gone in to arrest him or would it be the shop owner?

A stretcher was carried in and a little later it was brought out bearing a man. His eyes were closed and his face ghostly white.

âItâs Mr. Bickford!â Joe exclaimed.

Instantly the boys pushed through the crowd and rushed up to an officer just emerging from the store. He knew the Hardys and beckoned to them.

âWe were just a little too late arriving to catch Marr,â he said. âMarr must have attacked Mr. Bickford and cleaned the place out before he skipped.â

âA complete haul, you mean?â Joe asked.

âTook everything.â

âHow bad off is Mr. Bickford?â Frank inquired.

The officer shrugged. âHeâs unconscious and his pulse is weak.â

Joe spluttered angrily, âIf I get my hands on Marr, IâllâIâllââ

âItâs going to be rough tracking him down,â Frank predicted. âIâll bet by this time heâs wearing a disguise and has already left town.â

Joe snapped his fingers. âIf he owns a suitcase full of disguises, he probably went back to wherever heâs living to pick them up. Officer, have you any idea where heâs living?â

âNo, but our men are questioning people in the neighborhood.â

As the ambulance pulled away, the boys asked permission to check out the jewelry shop for a clue to Marrâs address.

The officer smiled. âGo ahead. You fellows may manage to pick up a lead before the police check. Iâm to stay on duty outside so take all the time you want.â

Frank told his brother he was sure Mr. Bickford had some kind of records concerning his assistant. No doubt they were under an assumed name. âLetâs have a look.â

The boys found a drawer full of papers. Under them was an account book. They read each name listed in the book and at last came to one with recent, regular notations of payments.

âThis might be his new clerk,â Frank observed. âRay Stokeley, 49 New Street.â

âItâs worth following,â Joe said.

Frank and Joe briefly told the officer on duty they might have a lead and dashed off to their car. They soon reached New Street, where most of the old-fashioned houses had âRooms for Rentâ signs in windows. Number 49 was a large run-down mansion, set far back from the street.

Frank and Joe climbed the high steps and rang the bell. A neatly dressed, middle-aged woman opened the door.

âIs Mr. Stokeley at home?â Frank inquired.

âNo, he has left-moved out, not ten minutes ago.â

The woman started to close the door, but Frank, smiling at her, said, âWe think heâs the man weâre looking for, but weâre not sure. Would you mind describing Mr. Stokeley for us?â

Her description fitted Marr. Frank nodded. âHeâs our man. Do you know where he went?â

There was no answer for a few seconds, then the woman said, âWho are you? Boy detectives?â

âYes,â Joe replied promptly, âand Mr. Stokeley is wanted by the FBI and police. Youâd be doing them a great favor if you tell us all you know.â

âOh!â she gasped. âI know very little about Mr. Stokeley. But I did hear part of a phone call he made early this morning. He said, âThen to the airport.â Does that help you?â

âYes indeed. Thanks,â Frank answered as he and Joe raced down the steps.

They arrived at the airport in record time. As they rushed through the terminal lobby, the boys glimpsed the pilot, Cole Weber, looking at the antique craft and waved.

âIf Marrâs wearing a disguise, how can we spot him?â Frank said.

Joe was staring at a man with gray hair, mustache, and a beard. He stood near a counter, talking to a red-haired fellow.

âFrank, look! That guy the gray-haired manâs talking to looks like one of the kidnappers!â

âSure?â

âPositive! And Iâll bet Gray Beard is Taffy Marr!â

The men turned and went out to the field. Frank and Joe followed. The suspects started running toward a small white single-engine plane that was ready for take-off. They climbed aboard quickly.

âNow whatâll we do?â Frank asked.

âOnly one thing we can do,â Joe replied. âFollow them!â

CHAPTER XV

Pursuit

âBUT how can we follow Marr?â Frank asked. âIf only Dadâs plane were here, we could do it easily.â

He was referring to the sleek, six-place aircraft owned by their father. However, Mr. Hardy and his pilot Jack Wayne had flown it to California with Mr. Wright.

âKeep an eye on that white bird,â Joe ordered. âIâll run into the administration building and telephone Agent Keith. Then Iâll go to Mansonâs Charter Service and see if we can rent a plane.â

âYouâd better make it quick!â Frank warned.

Joe rushed to a phone booth inside the administration building and dialed Keithâs code number. It took only seconds to make the connection.

âAgent Mallett speaking!â crackled a deep, firm voice.

âThis is Joe Hardy. Is Agent Keith there?â

âNo, but he should be back in a few minutes.â

âCanât wait!â Frank declared. âTell him my brother and I are trailing a man weâre sure is Taffy Marr. Weâre at Bayport field. The suspect and another man are about to take off in a white single-engine job. Weâll try to follow them. Iâll keep you posted!â

âGood work!â Mallett said. âTry to get the registration number of their plane so we can trace its owner.â

âRight!â

Joe hung up quickly and went directly to one of the terminalâs counters. Behind it stood a plump ish, pleasant-faced man. On the wall hung a sign which read:

MANSONâS CHARTER SERVICE

âWell, if it isnât Joe Hardy!â the man declared.

âHello, Mr. Manson.â

âWhere have you been keeping yourself? Havenât seen you around the airport lately.â

âWeâve been sleuthing,â Joe answered with a wink. âIâd like to charter one of your planes right away!â

âGosh, Joe, Iâm sorry, but all my aircraft are out on flights,â Manson said apologetically. âHavenât had such a busy day in months.â

Suddenly Joe had an idea. How about Cole Weber? He rushed off and in a few moments found the lanky owner of an antique plane.

âNice to see you again,â the pilot greeted him. âWhatâs the rush?â

âIâm looking for a ride.â

âYouâve come to the right man. Iâll be glad to fly you wherever you want to go,â Weber told him.

Joe drew the pilot aside and in a low voice briefly explained the situation to him. âCould your aircraft keep up with a fast plane?â

Frank rushed into the lobby. âMarr and his friend are getting ready to take off!â he exclaimed.

Followed by his brother and Weber, Joe ran to a window overlooking the field. They spotted the small, single-engine plane taxiing to the active runway for take-off. Frank jotted down the registration number.

âIs this the one you want to follow?â Weber commented. âThat type isnât too fast. Iâm sure I could keep up with it.â

âGreat!â said Frank.

âWeâll have to make it snappy!â Joe urged.

âMaybe not,â Weber answered. âThereâs a long line of planes waiting for take-off clearance. Itâll be at least ten minutes before those men can clear ground. Thatâll give me time to telephone the control tower. Since my plane is not equipped with radio, theyâll have to okay me for take-off by flashing a green light.â

Frank said, âHow about warning the control tower not to let Marr take off?â

Weber looked surprised. âAre you completely sure that one of those passengers is Marr?â he asked.

âWell, no, weâre not,â Joe confessed.

âThen I think weâd better not make such a request,â the pilot advised. âAll of us might get in trouble.â

The boys nodded and Joe said, âWeâll just make a chase of it.â

Weber went off but soon returned. âEverythingâs set,â he said. âAnd weâre in luck! The control-tower boys are going to let us take off from the grass shoulder of Runway Six. It means we wonât have to wait in line for clearance. Chances are weâll be off the ground ahead of your friends.â

The Hardys followed the pilot to his orange-and-white biplane. He drew three parachutes from the baggage compartment and instructed Frank and Joe to put them on while he fastened his own.

âClimb aboard!â he said.

The boys seated themselves side by side in the front cockpit. Weber signaled a mechanic to help start the engine, then jumped into the rear cockpit.

âBrakes on! Contact!â the mechanic shouted.

âBrakes on! Contact!â Weber replied.

With a single whirl of the propeller, the engine roared to life. The boys were so thrilled by the chance to fly in an old biplane that for a moment they had almost dismissed Taffy Marr from their minds.

Weber began to glide his wood-and-fabric craft down the taxiway. Nearing Runway Six, he veered onto the grass shoulder which paralleled it.

âAll set?â the boys heard him shout over the sound of the engine.

âAll set!â Frank and Joe answered.

Their pilot pivoted the craft around and pointed its nose into the wind. Shortly a bright disk of green light beamed from the control tower. The engine emitted a loud, steady roar as Weber advanced the throttle. The plane bounced across the grass surface, then cleared it. Frank looked down and spotted Marrâs craft just taxiing into position for take-off.

After reaching a couple of thousand feet, Weber circled the airport. He and the Hardys watched intently as the other plane sped down the runway and became airborne far below them.

Weber maneuvered his craft a safe distance behind Marrâs plane, which was now heading on a northeasterly course.

âSo far so good!â Frank exclaimed, noting that their quarry was not outdistancing them. The boys waved at Weber, who responded with a wide grin.

Nearly half an hour had passed when they noticed a build-up of haze ahead. It seemed to thicken as they drew closer. Soon the antique craft was skirting an ocean of milky-white mist which obscured the countryside below.

âWhat a cloud!â Joe shouted.

âAnd weâll head right into it on our present course!â Frank observed.

Weber signaled that he would try flying above it. By now Marrâs plane was also climbing. To the Hardysâ dismay, their quarry vanished behind a screen of whiteness.

Weber signaled that he was going to turn back. But as he banked the biplane, it suddenly plunged into a misty void!

CHAPTER XVI

Bail Out!

WEBER struggled to keep the aircraft under control in the fog. He shifted his attention to the turn-and-bank indicator mounted on the instrument panel. What the dial showed would help prevent the pilot from rolling into an uncontrollable spiral.

Then, suddenly, the plane broke out into a cavity of clear air. The boys spotted the other aircraft and saw that it had altered its course. It was now heading south. Weber immediately banked and took the same direction, hoping to close the gap and come in on the tail of the other plane.

It was then that the Hardys realized the extent of the fog bank. Already obscuring a great area of the coast, it stretched far out to sea. Ahead they saw their quarry flying directly toward a looming wall of thick mist.

Weber altered course again and headed northwest in an effort to skirt the edge of the fog bank. But the mist built up rapidly in swirling clouds.

âI guess if we hope to keep the other plane in sight, we canât go too far to the west,â Frank observed.

Weber began to climb, hoping to get above the fog. But as he turned north to meet the advancing cloud, his craft was enveloped in mist before he could gain altitude. Marrâs plane had vanished.

âThe other ship is equipped to fly on instruments !â Weber shouted. âWeâre not!â

Their pilot held to a straight course and increased his speed, hoping to run through the fog and pick up the other plane when visibility improved. The great bank of mist evidently extended over a greater area than he had first supposed.

Minutes ticked by and still the opaque grayness persisted. Frank and Joe turned to watch the pilot. Weber was peering at the instrument panel.

âAt least weâre flying straight and level,â he announced.

Frank and Joe tried to remain calm but inwardly they were worried. Their craft might ram another plane at any moment!

Weber continued on into the limitless white wall. Not a glimpse of blue sky. Not a patch of earth to be seen.

âI guess weâve lost Marr for sure,â Joe remarked.

âYes,â Frank agreed. His voice showed his disappointment.

Suddenly the roar of the engine stopped. The only sound was the hum of the rigging. The nose of the plane dropped sharply and the craft went into a dive.

âThe engine quit!â Joe yelled.

The pilot waved to them in an encouraging gesture. He had thrust the stick far forward and the plane was plunging through the fog at terrific speed.

On and on it went. The boys were alarmed. They knew engine trouble had developed and a forced landing in the fog would be perilous. But there must still be some hope; otherwise their pilot would have signaled to abandon ship.

The rush of air took their breath away. Then, as abruptly as it had ceased, the roar of the engine broke out again.

âBoy, what a welcome sound!â Joe exclaimed.

Weber eased the stick back slowly and the plane gradually recovered from the dive. It flattened out and began to climb again. Frank took a deep breath. Joe grinned.

But their relief was short-lived. Again the engine began to act up. It sputtered, balked, misfired, and picked up again. No longer was it throbbing with its previous regularity.

The boys looked back at the pilotâs anxious face. They all knew a blind landing could be disastrous! For a moment the Hardys stiffened as the engine died, then coughed once more.

âCarburetor ice, Iâll bet,â Frank said to himself.

The plane they had been pursuing was forgotten. Their whole concern now was safetyâto escape the gray blanket. If only they could sight ground to attempt a forced landing!

Frank felt for the harness of his parachute. âWe may have to jump,â he thought, not relishing the prospect. To leap from a crippled plane, with fog blanketing the earth below, was an experience he could do without.

Joe was alarmed too. âIf only the fog would lift!â

The pilot was desperately trying to revive the engineâs old steady clamor. But it was useless.

The engine quit again. The nose of the machine dropped and the plane repeated a long, swift dive. It straightened out, banked, then dived again at screaming speed.

Coming out of the second dive, the nose rose abruptly. They all waited for the reassuring catch of the engine but it remained mute.

The speed gained in the dive steadily decreased as the craft soared upward in a steep climb. Then it fell off on one wing and went into a descending spiral.

âI have a feeling weâre going in circles!â Joe shouted to his brother. âI think Weber is becoming disoriented.â

âWeâre sunk!â Weber yelled at the boys. âYouâll have to take to the chutes!â

âJump?â Joe shouted.

The man nodded. âThe engine is done for. Choked up. I donât dare try a landing in this fog. Weâll crack up sure. Hurry! Iâll keep her under control as long as I can. Crawl out on the wing, watch for my signal, then jump clear! Count ten, then yank the rip cord!â

The boys scrambled out on the swaying wing in dead silence as the plane coasted through the gray mist.

âJump clear!â Frank reminded his brother.

âItâs not the jumping that worries me,â said Joe. âItâs the landing.â

The boys knew that they had no control over their direction and had no idea of what lay beneath. They might be plunging directly toward a lake or into a city street!

Out on the wing Frank and Joe clung for a moment, their eyes on the pilot. Weber raised his hand, then brought it down sharply.

âJump!â

Since the parachutes could easily become entangled if the boys jumped together, Frank went first. He leaped away from the swaying plane and plummeted through the fog. Then Joe shot downward.

Twisting and turning through the air, the boys plunged toward the earth. Desperately Frank groped for the rip cord. It eluded his grasp. Sudden panic gripped him.

He was falling toward the earth at terrific speed and could not find the parachuteâs Dee ring!

Every second was precious. He knew that even if he found the ring, it would be a few moments before the parachute opened. By then he might already have reached an altitude too low to permit the chute to billow out in time!

Then his groping hand found the ring and he tugged. Nothing happened. He was still tumbling through the clouds of mist!

About to give up hope, Frank heard a crackling sound above him. There was a sudden jerk as though a gigantic hand had grabbed him. Frank found himself floating gently through space.

Through the wreaths of mist he glimpsed another object. It was a parachute similar to his own, dropping slowly through the fog. Joe, at least, was safe.

But what of the pilot and the crippled plane? Where were they?

CHAPTER XVII

The Trapped Pilot

FEAR gripping them, the Hardys drifted down silently through the fog. The only sound was an occasional flapping of the canopies looming above their heads.

âThe ground canât be too far below!â Frank thought. âWhat kind of terrain? Sharp rocks? Trees? Open water?â

He and Joe heard a muffled explosion some distance away.

âWeberâs biplane must have crashed!â Joe concluded. âHope he bailed out in time.â

Suddenly the milky void vanished. The Hardys blinked in relief. They were less than a hundred feet above a farmland area.

They settled down in a plowed field a short distance from each other. Frank tumbled across the soft ground a couple of times, then hauled in a section of shroud lines to spill the air from the canopy of his chute.

âYou all right?â he shouted to Joe, throwing off his harness and running toward him.

âIâm okay! That was wild! But I wouldnât want to do it again under the same conditions!â

Frank pointed to a plume of smoke rising behind a hill about half a mile away.

âThat must be the explosion!â he yelled. âLetâs see if itâs Weberâs plane.â

They raced toward the spot. In a few minutes they came to a charred, twisted mass of wreckage. A pool of oil still burned.

âAt least Weber wasnât in the crackup,â said Joe. âBut where is he?â

At that instant the pilot called out to them. âHey, fellows!â he shouted. âGive me a hand!â

The voice seemed to come from a small clump of trees located about five hundred feet away. When the boys reached it, they saw Weber dangling in his harness high among some branches.

âAre you hurt?â Joe asked with concern.

âNoâonly my pride,â the pilot answered. âIâm supposed to be an expert at handling a parachute. And where do I land and get trapped? In the only grove of trees within a mile!â

âYouâre too far above the ground to try dropping free,â Frank warned. âWeâd better get help.â

People from the surrounding farms who had seen the smoke began to arrive at the scene. When the boys asked for some rope, one of the farmers rushed off. He returned in a few minutes with a coil of one-inch hemp.

Joe took it and began shinning up the tree in which Weberâs chute had been snagged. Everyone watched the rescue as he edged out along a branch directly above the pilot and tied one end of the rope to it. Seconds later they both were sliding to the ground.

The farmer on whose property they had landed stepped up. âMy name is Hank Olsen,â he said. âWas anybody injured?â

âNo,â Frank replied. âSorry about the plane coming down on your land.â

âThatâs all right. I havenât done any planting in that section yet,â the farmer explained.

Weber spoke up. âIâd like to telephone a report of the crash.â

âYou can use the phone at my house,â Olsen offered. âIâll drive you there. My pickup truck is just on the other side of the hill.â

When they arrived at the farmhouse, the pilot called the control tower at Bayport field to report the accident. Frank phoned Mrs. Hardy to let her know where he and Joe were, and then got in touch with Chet Morton for a ride home.

âWhat!â Chet exclaimed in disbelief when he heard about the Hardysâ adventure. âSay that again.â

âI said we had to bail out of Weberâs biplane,â Frank declared.

Everyone watched the rescue

âAw, come on,â his chum muttered, unbelieving.

âItâs true,â Frank replied. âWe need a ride home. Do you think your jalopy would hang together long enough for you to pick us up?â

âHang together?â Chet retorted. âThatâs no way to talk about one of the finest pieces of machinery going. Where are you?â

Frank asked the farmer for their exact location. Olsen unfolded a road map and pointed to a spot about ninety miles northeast of Bayport. Frank traced the route with his finger and relayed instructions to his friend.

âOkay! Iâm on my way!â Chet answered.

Nearly three hours passed before the Hardys spotted their chumâs yellow jalopy bouncing along the narrow road leading to Olsenâs house. Weber and the boys thanked the farmer and his wife for their hospitality, then started for Bayport.

As they rode along, the Hardys and Weber discussed their pursuit of Marrâs plane. âI wonder if he ran into any trouble,â Joe mused.

âWhen I called control tower, I asked if they knew about the stretch of fog north of them,â Weber explained. âThey did, and said it was only two or three miles across, with clear air on the other side.â

âAnd since Marrâs plane was equipped with radio,â Frank interrupted, âthe pilot would have received the latest weather reports. He knew he could fly through the fog bank and be in the clear again within a few minutes.â

âDo you think Marr knew he was being followed?â Joe asked.

âMy guess is he didnât,â Weber said. âAt least his pilot wasnât attempting any evasive action.â

âSorry about your plane,â Joe said sympathetically.

âIt was a great ship,â Weber declared sadly. âBut I have enough parts to rebuild another one. Thatâs some consolation.â

Chet dropped off Weber and the Hardys at Bayport field, where the pilot made arrangements to fly home. After expressing their thanks to him for his help and saying good-by, the boys walked toward their car.

âWeâd better call Agent Keith before we go home,â Joe suggested, and they went inside to telephone.

âToo bad Marr got away,â the agent said when Frank told him about their recent adventure. âBut Iâm glad you and your brother are safe.â

Frank drew a notebook from his pocket and opened it. âI have the registration number of the getaway plane.â

âGood!â Keith said. âLetâs have it. Iâll check it out with the Federal Aviation Agency.â

Frank gave it and hung up. The boys went to the parking lot. In a moment Frank frowned. âI thought I left our car here.â

âYou did,â Joe said with a sinking feeling. âItâitâs been stolen!â

The Hardys were momentarily paralyzed. Not only their fine convertible, but Mr. Wrightâs highly secret invention was gone!

Frank spoke first. âCome on, Joe! We must call the police.â

The boys ran to the administration building and telephoned. They were told by the sergeant on duty that state troopers had picked up a car fitting the convertibleâs description. âWill you Hardys go out to the end of Pleasantdale Road and look at it?â the officer requested.

Frank hailed a taxi which took them to the spot, then back to Bayport. The convertible was a sorry sight. Every bit of the upholstery had been slashed and the contents dumped out. Articles had been removed from the front compartment and the trunk. The spare tire had been ripped open.

âToo bad, fellows,â a trooper said.

âYes,â Frank answered, testing the rack.

It was still bolted in place, but he winked at Joe, a signal he wanted to be alone for a further search. On a pretext Joe got the trooper around to the front of the car. Quickly Frank looked under the tire well. The box and invention were still there

Frank slammed the lid shut. He called out, âJoe, if this baby still runs, letâs go home.â

The engine started promptly and the steering mechanism was undamaged. Frank signed a paper for the police, saying he was the owner of the car, then the boys rode off. As soon as they reached home, Joe carried the invention to the boysâ room and hid it.

âIâm afraid that next time the gangâs going to find this,â he told his brother.

âI agree,â Frank answered. âWhat say we ask Mother to put it in her safe-deposit box? Iâm sure Dad would agree.â

Mrs. Hardy and Aunt Gertrude approved this idea and as soon as the bank was open the next morning took the invention downtown. A little later the phone rang. Mrs. Hardy was calling to assure her sons of its safety.

A few moments later Agent Keith telephoned. âWeâve lost Marr again,â he said. âThe FAA looked up the registration number of his plane. It belongs to a fixed base operator at a small airport in Connecticut. Marrâs pilot rented the plane for the day.â

âDid the owner see the pilotâs flying license?â Frank inquired.

âYes,â Keith replied. âThe name listed was Harold Clark. Itâs a forgery! Such a license was never issued!â

âWhat about the plane?â

âIt was returned sometime last night. The owner found it tied down on his ramp when he went to the airport early this morning.â

The Hardys were downcast by the situation. Marr had vanished and they did not have the slightest lead on him. Furthermore, their car was a wreck. They reported the damage to the insurance company and waited for an investigator to come.

âWeâll have to rent a car while ours is being repaired,â Frank said.

He made the arrangements by phone and within half an hour a car stood in the driveway.

The boys had just sat down to lunch in the dining room when the telephone rang. Aunt Gertrude went to the kitchen to take the call.

âYes, theyâre at home,â the others heard her say. Presently she darted into the room. âItâs about Mr. Bickford!â she said quietly.

CHAPTER XVIII

Outsmarting the Enemy

MRs. HARDY and her sons lowered their eyes. They were sure Aunt Gertrude was about to announce that the kindly jeweler had died because of Marrâs beating.

âMr. Bickford isâisâ?â Frank asked.

âHe wants to see you at the hospital,â his aunt replied.

âThen heâs alive!â Joe exclaimed.

âOf course heâs alive,â Aunt Gertrude said. âVery weak naturally, so I donât think you boys should stay long.â

âWhen are we to go?â Frank asked.

âMr. Bickford got permission for you to come any time. He has something urgent to tell you.â

Curious as to why they were being summoned, Frank and Joe left immediately to see the elderly man. Mr. Bickford was partially propped up in bed. He looked ill, but he gave his visitors a warm smile.

âIâm so glad you came,â he said in a voice barely above a whisper. âThe doctor said a ten-minute visit so Iâll get right down to business. Sit down, please. I feel it my duty to warn you boys.â

âWarn us?â Frank asked. âAbout what?â

âThat clerk who slugged me and his pals are determined to get you,â Bickford answered. âStokeley thought he was in the shop alone, but I came in the back door quietly. He was talking on the phone and seemed to be giving orders.â

Mr. Bickford stopped speaking and closed his eyes. He began to gasp a little. Frank jumped up and pressed a cup of ice water to the manâs lips. Mr. Bickford sipped it gratefully.

âPerhaps we should go,â Frank suggested.

âNo, no, not yet. This wonât take long,â Mr. Bickford insisted, opening his eyes again. âI must tell you. Stokeley was saying, âDonât tell me you couldnât help your bonehead mistakes. Just donât make any more! I want the Hardys on the whaler.â

âJust then Stokeley caught sight of me and hung up the phone. He turned livid, and before I could defend myself, he punched me, kicked, hit me with a stool, and acted like a crazy man. I blacked out and awoke here.â He closed his eyes and shuddered a little.

Frank and Joe stood up, sensing that Mr. Bickford was exhausted and had told all he knew.

âThanks a lot,â Frank said. âJoe and I are certainly sorry we were the cause of the attack on you.â

âAnd weâll profit from your warning, you can bet,â Joe added. âNow take care of yourself.â

When Frank and Joe reached home, they at once told their mother and aunt about Mr. Bickfordâs report. âSo you see, Aunt Gertrude,â said Joe, âthat man Chris wasnât calling you an old whaler. He was talking about trying to get us boys on their motor whaler.â

âHmm!â said Aunt Gertrude. âWell, just the same he has very bad manners. Doesnât know how to treat a lady.â

Mrs. Hardy was extremely concerned and said so. âI believe if Joe hadnât been rescued from that cave, those dreadful men would have put him aboard the whaler and taken him far away. Frank would have been next.â

âExactly,â said Aunt Gertrude, âand Iâm sure your father never intended you boys to become so deeply involved in this horrible case. I believe my brother would thank you, Laura, to forbid these boys from any further detective work against such men as Taffy Marr.â

Frank and Joe were fearful their mother might take Aunt Gertrudeâs advice. After several moments of silence, Mrs. Hardy answered. âFenton expects his sons to follow through and see justice done. He doesnât want me to pamper them into being cowards. However,â she added, âI expect them to be cautious and alert. Frank and Joe donât deliberately run into trouble.â

The boys were relieved. Each kissed their mother and thanked her for her confidence. Now that the tension was over, Joe grinned and said, âMother, we should have been born with extra eyes in the back of our heads, so we could see in all directions.â

âYou could wear those special spectacles that reflect whatâs in back of you,â Aunt Gertrude suggested.

âBut they donât work at night,â Joe replied, âand thatâs when most of the sluggings take place.â

The conversation was interrupted by the door-bell. Frank answered and was handed a special-delivery letter.

âItâs for you, Mother. From Dad,â he called.

Mrs. Hardy opened the envelope quickly. Presently she said, âGood! Your fatherâs coming home. That will solve a lot of problems.â

She read farther. âBut not right away. He and Mr. Wright have to testify against two men suspected of stealing the antique plane.â

âDad found it?â Joe burst out.

âYes. Listen to this: âI have good reason to believe the hijackers are part of the gang Iâve warned the boys about. Iâm sure these men have pals who are watching me, tapping my phone, and intercepting radio messages, so I decided to use the mail. In an emergency you can contact me in care of Elmer Hunt, president of the Oceanic Electronic Company, San Francisco.ââ The rest of the note was for her personally.

Frank and Joe went upstairs and discussed their next move. Both agreed they should do everything possible to learn where the whaler was moored.

âI guess it wouldnât be too smart to use our Sleuth to hunt down the whaler,â Frank remarked. âWeâd be spotted in a moment. And anyway we havenât fixed the horn yet.â

âI donât think itâd be good to take Tonyâs boat, either,â Joe said. He was referring to their school friend Tony Prito.

âHow about arranging with somebody who has a cabin cruiser to help us make a search?â Frank suggested.

Joeâs eyes twinkled. âPretty expensive. How about the tug that nearly rammed you in the fog. Was there a name on it?â

âIâm not sure, Joe. I was pretty busy getting out of the way! But it seems to me I saw the word Annie on the side.â

The boys decided to go to the docks on their motorcycles. These were easier to maneuver and hide than their rented car.

Soon after they left, Frank and Joe noticed that a car with three men in it was following them. None of the passengers looked familiar.

âWeâd better do something fast and shake off those men!â Frank advised.

âGuess weâll have to play hare and hounds,â Joe observed. âWhat do you suggest?â

âHead for Biff Hooperâs and pretend to be staying there,â Frank answered. âWe can sneak out their rear door before those men have a chance to go around to the garden.â

Joe nodded. âAnd take a back street to the docks. Score one for us!â

They explained their plan to Mrs. Hooper, who let them out the kitchen door. Frank and Joe hurriedly crossed the rear lawn, which was out of sight of the street. They jumped the hedge. Twenty minutes later the Hardys were in Harbor Master Croganâs office inquiring about a tugboat named Annie.

The man flipped open a large ledger and ran down a list. âI guess you mean the Annie K. She comes in here once in a while.â

âIs she docked now?â Joe asked.

âIâll see.â Crogan consulted a chart on the wall. âYes, she is. Waiting for some kind of shipment thatâs been delayed.â

Frank and Joe glanced at each other. There might be a chance of chartering the tug!

âDoes the captain own the Annie K?â Frank inquired.

âYes, and a real nice man he is too. Nameâs Captain Volper.â

The Hardys got directions on where to find the tugboat, thanked Crogan, and left. Captain Volper was seated cross-legged on the deck of the Annie K, reading the morning paper. He was a ruddy- complexioned, slightly plump, good-natured man.

âHowdy, boys!â he greeted the brothers. âAnd what can I do for you?â

Frank made their request.

âSo you want to take a cruise around the bay, up and down the coast, eh? Well, I guess I could do it.â He laughed. âYou fellows got some money with you?â

âSure thing,â Frank replied. âCan we cast off now?â

âSoonâs I can get my crew out oâ the coffee shop across the street.â

He ambled off down the gangplank and was gone nearly fifteen minutes while the boys walked up and down impatiently. Then Volper returned with two sailors, whom he introduced as Hank and Marcy.

A few minutes later the old tugboat pulled away from the dock. The boys decided to stay in the cabin so as not to be seen by anyone going past in other boats.

âCaptain Volper, did you ever notice a motor whaler around here?â Frank asked.

âYes, about two weeks ago. Then I got caught in the fog and plumb near run somebody down.â Frank and Joe glanced at each other.

âDoes the whaler have a name on it?â Joe asked.

The captain tilted back his cap and scratched his head. âSeems to me it did. Thatâs harbor regulations, you know. Let me see now.â Unable to recall the name he summoned Hank and Marcy and asked them.

âSure I remember it,â Marcy replied. âMan alive, I wish I could own one oâ them plastic boats. They got speed. The name oâ this one I seen anchored up near the caves was Water Devil.â

âIâll bet it is, too,â Joe commented, but did not explain the double meaning in his remark.

The tug went directly to the spot and the boys gazed at the sleek whaler, which was anchored in shallow water. No one seemed to be around.

âShip ahoy!â Volper shouted. There was no answer.

âIâm going aboard,â Frank announced. When the captain reminded him that the law dealt harshly with snoopers, the young detective said, âDid you know smugglers are operating in this territory?â

Volper and his crew were amazed.

âAnd you think this is their boat?â the captain asked.

âWe suspect so,â Frank replied. âWeâd like to go aboard and hunt for clues.â

The captain sighed. âBoys today are too smart for me. Go ahead.â

He pulled up close to the whaler and the Hardys jumped down onto the deck of the Water Devil. At first they made a casual surveillance. Seeing nothing suspicious, the boys began opening lockers.

âThis is the gangâs boat all right,â Joe sang out, holding up a piece of paper with red and blue stripes on it. A few figures had been scrawled on it.

âSay, Frank, do you suppose there are any diamonds or electronic equipment hidden aboard?â

âLetâs look!â

Nothing came to light until they opened a dashboard compartment. A sack lay inside. Both boys reached for it at once. The next second they were hurled violently across the deck. They blacked out and toppled into the water.

CHAPTER XIX

Anchor Pete

ON the deck of the Annie K, Captain Volper and his crewmen stood stunned by the sudden accident. But not for long. Instantly Hank and Marcy jumped into the water.

âIâll get this one,â Hank called, indicating Joe as the boyâs limp form bobbed to the surface.

Marcy set off with fast strokes to rescue Frank. In less than a minute the two Hardys were lying on the deck of the tugboat and being given first aid. They did not respond.

âWeâd better get these boys to the hospital as soon as possible,â Captain Volper said worriedly.

He set the shipâs engines to maximum capacity and sent a radio message for an ambulance to meet him at the dock. By the time Frank and Joe regained consciousness, they were in a Bayport Hospital room and Dr. Bates was there, as well as Mrs. Hardy and Aunt Gertrude.

Relief spread across the watchersâ faces as the boys managed wan smiles. âI guess we gave you all a good scare,â Joe remarked. âSay, where are we?â

When the boys were told, Frank said, âJoe and I must have been out a long time. I remember we touched a sack in that whaler and then-wham! What happened to us?â

âYou fellows got a bad electric shock,â Dr. Bates explained, âand were thrown into the water. If Captain Volper hadnât been there, you would have drowned. Hank and Marcy rescued you.â

âThank goodness,â Mrs. Hardy murmured.

âThe person who rigged up that device got a shock of his own,â Aunt Gertrude said crisply, âand Iâm glad he did.â

âHe was caught?â Joe asked. âWho is he?â

âYour kidnapperâat least this is what the police think from your description of him,â Aunt Gertrude said. âWhen you feel well enough, youâre to go down to headquarters and identify this man you call Gross.â

âHow was he captured?â Joe asked impatiently.

The boys sat open-mouthed in astonishment as they listened. Captain Volper had notified the Coast Guard and the Harbor Police. Both had gone out at once to the spot where the Water Devil was moored. Nothing had been disturbed and the men were sure no one would show up until the launches moved away.

âThe police decided to leave a couple of their skin divers to watch,â Dr. Bates told Frank and Joe. âSoon after the others had left, a rowboat came from shore. The man in it boarded the whaler. He looked worried at seeing the compartment open, but seemed relieved that the sack was still there. He clicked off a switch, then picked up the sack with no harm to himself. As he reboarded the rowboat with it, the man was overpowered by the two skin divers.â

âWhat was in the sack?â Joe queried.

âExactly what you might expect,â Aunt Gertrude said. âDiamonds and valuable electronic equipment.â

Mrs. Hardy told her sons that both the Water Devil and the rowboat had been impounded by the authorities and were being examined for further clues since the prisoner would reveal nothing.

Joe wanted to go right down to headquarters and see the man, but Dr. Bates forbade this.

âMay I call Chief Collig?â Joe asked.

A phone was brought to the room and plugged in. Soon Joe was talking to the chief, who was amazed and delighted that the Hardys had recovered.

âI want to see the prisoner,â Joe told him. âDr. Bates says I canât come down. Could you possibly bring him here?â

The others in the room gasped at the request, but Dr. Bates nodded his approval after the chief had said, âIf the doctor thinks itâs okay.â The physician left but Mrs. Hardy and Aunt Gertrude remained.

Twenty minutes later the prisoner arrived with two officers, one of them with a tape recorder already turned on.

âHeâs Gross all right!â Joe burst out. âMy kidnapper!â

The man was sullen. He murmured defiantly, âYou canât prove a thing.â

âProof?â Joe scoffed. âI heard plenty in the cave. And somebody else besides me got a look at you when you were snooping in our car.â He did not mention Iolaâs name.

When Gross made no answer, Aunt Gertrude cried out, âYou ought to be horsewhipped! Jailâs too good for people like you. Kidnapper, smuggler, and goodness knows what else!â

As she paused to take a deep breath, Frank spoke up. âGross, you tried to starve my brother and you doped him.â

The prisoner finally began to talk. âIâI had to do what I was told or risk being killed myself.â

âYou mean by Taffy Marr?â Frank shot at him.

Gross winced. âYes. I shouldnât tell you, but it donât matter now. I got nothing to lose. Marr takes away every diamond and electronic gadget we steal and smuggle in and threatens us besides. Iâm better off in jail.â

One of the officers remarked, âThings will go a lot better for you if you tell everything. Where is Marr now?â

âI donât know. He was watching me from shore with binoculars. When I got caught Iâm sure he ducked into hiding. Thatâs the way he does. When things get too hot, every man for himself. Then in one month we meet up again.â

âWhatâs the next place?â the officer asked.

âPortland, Maine.â

âNo plans until then?â

Several seconds passed before Gross answered. Finally he said, âEach man was ordered to get the Hardy boys one way or another. Maybe some of âem will still stay around here and try it.â

âOh, I hope not!â Mrs. Hardy exclaimed.

Frank asked the prisoner, âWho do you think will get after us first? And where?â

Gross did not answer directly. âI donât want to see you guys get hurt, but I canât help you. Chris might decide to stick around or Anchor Pete.â

âAnchor Pete?â Joe repeated.

âYeahâheâs a sailor and a smuggler. Used to pitch an anchor like youâd pitch horseshoes and bet he could throw one fartherân anybody else. He could, too. You guys had better watch out.â

Gross, who finally said his first name was John, had no record. Marr had saved him from being beaten up by a gang, so Gross had felt indebted to him. âBut I was wrong. He made a no-good out oâ me. And what do I get? Jaillâ

The bitter prisoner was led away. A nurse came in with food for the boys and announced that as soon as they had eaten they were to go to sleep.

Mrs. Hardy and Aunt Gertrude kissed Frank and Joe good night and left. As the boys ate, they discussed the latest developments in the case and how they should tackle them when they resumed their detective work.

âI have an idea,â Frank said. âHow about asking Chet and Biff and Jerry to shadow us while we let ourselves be seen around?â

Joe grinned. âHoping to be attacked, you mean?â

âRight.â Frank thought it doubtful this would occur in daylight. âWeâll reverse our scheduleâsleep in the daytime and roam at night.â

From his bed Joe shook hands with himself, indicating, âAgreed.â

Three days went by before Dr. Bates told the boys they were âas good as new. And stay that way!â he advised with a meaningful laugh.

Meanwhile, Frank and Joe had arranged with their friends to carry out the sleuthing program.

âOkay,â said Chet, âbut I think your scheme is pretty risky. Taffy Marr may have shadows following his men and they could be behind the other fellows and me.â

âWeâll just have to take that chance,â Biff had said.

The first night was spent along the waterfront where the Hardys were sure Anchor Pete would be stationed. Frank and Joe walked together at times, then would separate. They deliberately went into dark areas and deserted spots. No one bothered them and later their friends reported having seen nothing suspicious.

âTomorrow night,â said Frank as the group separated, âweâll try the high school and athletic grounds and football stadium.â

Again the boys were not disturbed and so far as they could judge were not followed.

âWhatâs next?â Biff asked.

Joe felt that perhaps Marrâs gang had learned the Hardysâ friends were helping them and suggested he and Frank try the sleuthing alone.

âNothing doing,â Chet spoke up.

It was decided that the third night would be spent in the heart of town and would last only until just before midnight. It rained, but once more Frank and Joe led the way through dark streets and up and down deserted alleys. Finally, at ten minutes to twelve, they heard Biff whistle, Jerry give the sound of a hoot owl, and Chet yip like a dog.

âQuitting time,â Frank remarked.

âYes,â Joe said. âThree nights of walking and not one thing happening. By this time Marr and the rest of his gang could be halfway around the world.â

Frank sighed from weariness and disappointment. âLetâs take a short cut across the square.â

They headed for the small park which lay in the center of Bayport. Various municipal buildings, including the town hall with its large illuminated clock, outlined the four sides.

Frank and Joe reached the square and took a diagonal path through it. The place seemed empty. Part way across, Joe suddenly said, âI just saw someone dodge behind that big tree ahead.â

âWeâd better wait,â Frank answered.

The Hardys jumped back of a wide-trunked maple. When no one ventured toward them, the boys peered out, looking in opposite directions for a possible attacker. Seconds later there was a shuffling sound behind them.

âLook out!â a voice yelled.

Frank and Joe turned in time to see a masked sailor swinging a heavy anchor. He was about to crash it on Frankâs head!

CHAPTER XX

Captivesâ Hideout

THE sailorâs diabolical move was accompanied by the midnight striking of the clock, shouts from all directions, and a prolonged war whoop that could come from no one but Chet Morton. As Frank and Joe dodged the anchor, footsteps pounded in their direction.

The boys grabbed the sailor and held him tightly. In a moment Chet, Biff, Jerry, and Mr. Hardy rushed up.

âDad!â his sons cried. âWhen did you get home?â

âI havenât been home yet,â the detective answered. âCame from the airport and dropped off Mr. Wright. As I rode past here, Chet hailed me.â

Frank stared at the other boys and said, âI thought youâd gone.â

âWhat do you take us for?â Chet asked. âDid you think weâd run out on you? We were planning to follow you to your house.â

All this time the sailor was wriggling, trying to break away from his captors.

Joe looked at him hard. âHold still, Anchor Pete!â he ordered. âYouâll stay right here until the police come for you.â

âAnd his pal,â Biff put in. âI kayoed him back by that tree.â

The sailorâs jaw dropped. âBen?â he said unbelievingly. âAnd you know my name too?â

âSure,â Frank answered. âYour buddy Gross squealed.â

Meanwhile, Mr. Hardy had pulled his two-way short-wave set from a pocket and began talking to police headquarters. He told what had happened and asked that Keith and Mallett of the FBI be notified. The sergeant agreed and said he would send a squad car and four men to the park immediately.

While waiting, Frank and Joe asked the other boys to hold the captive sailor so they could go look at Biffâs victim. When Joe beamed his flashlight on the manâs face, he exclaimed, âThis guy was in the cave with my kidnapper!â

The boys dragged the man back to where Anchor Pete was standing. The sight made the sailor blanch and the Hardys figured that maybe he was so frightened he might talk if quizzed.

âPete, the gameâs up!â Frank said. âYou can tell us about Taffy Marr now.â

The sailor squinted his eyes and looked into space, as if trying to make up his mind what he should do. At last he said, âIâll talk. Marrâs gone to make a pickup.â

âDiamonds? Electronic parts?â Joe asked.

âYeah.â

âWhere?â

âAlong the bay. Maybe near the caves.â

At that moment the police car arrived and the two prisoners were put inside. Before the driver pulled away, he said to the Hardys, âSergeant asked me to give you a message. Keith and his assistant Mallet are already in town. Theyâre at your house.â

The Hardys said good night to Chet, Biff, and Jerry, thanking them for their fine work.

âAny time,â the three responded.

On their way home Frank and Joe asked their father how he had learned about the gang. âI got a tip from a detective friend in Chicago, but he wasnât sure just which gang it was.â

When the three reached home they found Mrs. Hardy and Aunt Gertrude with the two FBI agents. They had already briefed the men on the latest developments in the case.

âOur nightâs work isnât finished,â Frank spoke up. âWe have a new lead to Taffy Marr.â

âWeâll go right after him,â Keith said.

âAs soon as we put on dry clothes and get raincoats,â Mr. Hardy said.

Within ten minutes the five were ready to leave the house. Mr. Hardy drove his car. The gentle rain had now changed to a severe storm. Thunder boomed and vivid flashes of lightning streaked down from the black sky.

When the Hardys and the two agents reached the area of the caves, the detective parked and the searchers groped their way down the hillside.

âThereâs a narrow path between the cliffs just ahead,â Frank told the others. âIt leads directly down to the water.â

He led the way to the path and started down it. The teeming rain made the footing treacherous. Occasionally a flash of lightning illuminated the entire hillside, forcing the sleuths to crouch low to avoid detection.

During one of the flashes, Joe pointed to the shore below. âI saw a man standing down there! He could be Marr!â

The searchers continued to stalk their way along the steep path. When they were a little more than halfway to the bottom, Mr. Hardy signaled for his companions to stop.

âKeith, how about our sitting here for a while and seeing what that man is up to,â Mr. Hardy whispered. âThis spot is a good vantage point, and there are enough bushes to provide cover.â

âGood idea.â

As they watched the shore below, the watchers suddenly saw a flashlight beam flicker on and off several times.

âMarr must be signaling to someone,â Mallett said.

âWhatâs that?â Keith snapped, pointing off into the distance.

There had been an answering gleam from far out in the bay. The light flashed once, twice, then out completely.

A few minutes later there was a flash of lightning that bathed the entire area in a livid glare. In that moment the boys and their companions caught a glimpse of a small rowboat making its way inshore across the choppy waters.

âDid you see that?â Frank cried. âFour men in that boat.â

âLetâs go down for a closer look,â Joe suggested.

They descended cautiously, edging their way through the bushes toward the spot where the man was standing. Through the storm they heard a faint shout. Again the suspect signaled with his flashlight. He was guiding the boat inland.

As it drew closer, the sleuths heard the rattle of oarlocks and advanced a bit. Then, about forty feet away, they could clearly distinguish the waiting figure near the waterâs edge.

The gangleader switched on his flashlight again. The rowboat was approaching. It rocked to and fro with its bow high.

âThat you, Marr?â someone called.

âYes, but shut up!â

At last they were going to confront Marr!

âWe canât risk letting those men get away,â Keith muttered. âWhen the boat lands, weâll arrest them!â

The agents drew their pistols. With Mr. Hardy they poised for action. The detective ordered his sons to step back.

The rowboat was now in shallow water. Two of the occupants leaped out and pushed the craft onto the beach.

âThis is it!â Keith declared. âLetâs go!â

He sprang from the bushes with Mallett and Mr. Hardy.

âPut up your hands!â the agent shouted. âAnd donât make a move!â

There was a yell from the dim figures on the beach. One of the men was about to push the rowboat back into deep water, when Mallett fired two shots over his head.

As the agents ran toward the suspects, Frank caught sight of a man running down the beach and raced after him. Behind him he could hear shouts, another shot, then the sounds of a struggle.

The fleeing man plunged on into the darkness, but the young detective overtook him quickly. His quarry suddenly turned, crouched low, and as Frank came up he lashed out with his fists.

The boy dodged the blow, then grappled with the man. A clenched fist struck the young sleuth in the face and sent him sprawling.

Frank recovered instantly and scrambled to his feet. His opponent turned and fled. Again Frank overtook him and brought the man down with a flying tackle. In a tight clinch they rolled across the beach and into shallow water. Finally Frank managed to get in a blow that knocked his opponent unconscious. He dragged him out of the water.

Joe, meanwhile, had plunged knee-deep into the water and grabbed a man who was trying to haul the boat away from shore. They lashed out at each other. Joe was knocked down. He struggled to his feet, choking and gasping, and followed his tall, muscular opponent onto the beach. The man aimed a blow, but Joe side-stepped it, then rushed in and drove his fists into the otherâs body. The gangster grunted and doubled up with pain.

Joe noticed that Mallett was sprawled on the ground apparently unconscious and that Mr. Hardy and Keith were still battling two men.

Joe suddenly realized that Taffy Marr had escaped and was now rowing off in a sheet of rain.

âMarr is getting away!â he shouted.

âWhat!â Keith yelled. âAnd we donât have a boat to go after him!â He fired a shot in the air, but the suspect did not halt.

Mallett recovered and got to his feet just as Frank arrived, shoving his prisoner ahead of him.

âMarr escaped in the rowboat!â Joe told his brother, and picked up the flashlight Marr had dropped. He directed its beam on the prisoners.

âI recognize three of these guys!â he exclaimed as Keith and Mallett handcuffed the men. âThey visited Chris in the cave when I was there.â

They were frisked and bags of diamonds and small electronic equipment removed from their pockets.

âWhereâd you get these?â Mr. Hardy asked.

âTheyâre legit,â one man said.

âWe know youâre smugglers,â the detective said, âand we can trace these.â

âOkay. They were dropped to us off a ship. In this storm I didnât see the name of it.â

âWhereâs Marr going?â Frank asked one prisoner.

âYouâre not gettinâ anything more out of us!â

âThatâs not being smart,â Keith said. âAfter all, Marr left you behind to face the music. It might help you get off with lighter sentences if you cooperate.â Silence.

âWhy donât you tell us what you know?â Frank queried.

âIâI want to,â the man stammered. âBut Iâm afraid ofâof the boss.â

âYou mean Marr? Where is he?â

âI guess up on the north shore of Barmet Bay. Place called Rocky Point. Marr had me rent an old shack there. He uses it as a hideout.â

âWhereâs Chris?â Joe questioned.

âProbably waiting for Marr.â

Mr. Hardy radioed Bayport Police Headquarters again and said they had captured more of the smugglers. The sergeant promised to notify the Harbor Police to pick them up.

âI hope they come soon,â Joe said. âWe must go after Marr before he skips.â

The launch arrived in an incredibly short time and the prisoners were handed over. Then Frank said to the captain, âWe may need you again soon. Up at Rocky Point.â

âLet us know,â the skipper said and chugged off.

The Hardys and the FBI agents climbed the cliff, then rode along Shore Road to Rocky Point. In this area the bluff was not so steep and the sleuths had no trouble descending it. They were just in time to see a man with a lantern meeting an arriving rowboat.

âThatâs Chris!â Frank whispered.

âAnd Marr,â Joe added. âLetâs rush âem!â

âNot yet,â Keith said. âI have a tape recorder in my pocket. We may find their conversation useful.â

As Keith had hoped, the two smugglers talked freely.

âI guess now we clear out of Bayport for good,â Marr said. âChris, when we get to Portland, you set up a whole new gang. Make friends with the crew of a new ship and pick out one like Beef Danion on the Rizzolo. Too bad to chuck him.â

âBut, Taffy,â said Chris, âyou goinâ to leave here without getting Wrightâs secret radio? You said that if you used that, nobody could ever catch us. It would scramble messages among the gang and from ship to shore. And the dicks couldnât interfere, or a bad storm stop your orders from reaching us.â

âI know,â Marr answered, âbut right now our skinâs more important. Maybe I shouldnât have hung around after I slugged Bickford. But I needed tonightâs haul.â

âWhat about your stealinâ Wrightâs antique plane?â Chris asked.

Marr gave a sardonic laugh. âIt served its purposeâkept Mr. Wright and Mr. Hardy away from here. But those kids, Frank and Joe, are pests. All the Hardys are too clever.â

The boys were smiling. Marr did not know that one of the secret radios was hidden in Wrightâs plane, and now it had been recovered!

By this time Marr and Chris had reached the one-room shack and went inside. Again the boys wanted to rush the place, but their father held them back.

âYou watch through that window,â he ordered.

Going off a little distance, the detective radioed the Harbor Police.

Then he and the FBI men got set to burst open the unlocked door. Inside, the smugglers were busily packing suitcases. They had stopped talking.

At a signal Keith opened the door and dashed into the room with Mallett and Mr. Hardy. Taken by surprise, Marr and Chris had no chance to put up any resistance and were handcuffed to await the Harbor Police. When Frank and Joe came in, they received looks of furious resentment from the prisoners.

Meanwhile, the smugglersâ tricky suitcases were examined. Many secret pockets and a false bottom were found, each containing a fabulous quantity of jewels and electronic equipment.

Joe broke the silence. âWowee, these smugglers could have retired rich!â he remarked.

Presently the police arrived and the two men were taken away. Keith and Mallett went with them. As the launch departed, Frank and Joe realized that another mystery had also departed. They were to experience a âlostâ feeling until their next case, While the Clock Ticked, came along.

On the way home, the boys and their father filled in the gaps of the present mystery. âMr. Wright is very pleased with your work,â said Mr. Hardy, âbut heâs ready to sell his antique plane.â

âWe know who will buy it,â Joe spoke up. âCole Weber.â

âWhat about the special radio, Dad?â Frank asked. âSurely thereâs more to it than what we know.â

Mr. Hardy chuckled. He did not answer directly and they guessed the secret was a highly classified one. Instead, he said, âSomeday how would you boys like to own pocket radios that can pick up signals from outer space?â

âYou mean thatâs what Mr. Wright has done?â Joe cried out.

The detective gave his sons a broad wink.