THE MYSTERY OF THE SPIRAL BRIDGE

FRANK and Joe Hardy are determined to bring to justice the vicious criminals who kidnapped their detective father while he was investigating sabotage of a road-building project in the Kentucky wilderness.

After Mr. Hardyâs amazing escape, the boys pick up a clueâthe word âFelixâ mumbled by their sick father in his delirium. When they discover that the dossier of a notorious ex-convict has been stolen from Mr. Hardyâs files, the two young sleuths are doubly spurred to action.

The trail leads them to New York City but ends abruptly in a cemetery! Stunned, Frank and Joe come upon another clueâa spiral symbol. Aided by their pals, the boys take jobs on the highway construction crew in Kentucky to try to track down the kidnappers and the nefarious saboteurs. But who among the crew is friend and who is foe?

In a desperate maneuver that almost costs them their lives, the Hardys bring to a spine-tingling close one of the most action-packed and suspenseful mysteries they have ever solved.

The huge bear lunged from the cave

Copyright Â© 1994,1966 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 : 978-1-101-07658-3

2008 Printing

http://us.penguingroup.com

CHAPTER I

Bad News

âCHECKMATE!â said Frank Hardy as he glanced across the chessboard at his brother Joe.

âOkay. Youâve got me.â Joe frowned at his trapped king. âI canât keep my mind on the game, waiting for that call and wondering how Dad is.â

Dark-haired Frank, eighteen, and blond Joe, a year younger, sat in their laboratory next to a short-wave set. The room, filled with the latest scientific and detecting apparatus, was located over the garage behind the Hardy home in Bayport. Suddenly a metallic voice filled the lab. Both boys became tense.

âRadley calling Frank and Joe! Do you read me?â

âRoger,â replied Joe. âWhere are you, Sam?â

âFifty miles from Bayport. We ran into a storm which slowed us down. Jack Wayne is preparing to land. Incidentally, boys, weâve been tailed all the way from Kentucky! The other plane keeps just far enough away so we canât identify it.â

Frank pushed closer to the microphone. âHowâs Dad?â

âSorry. No change.â

âWeâll have an ambulance waiting,â said Frank.

âRoger. Over and out.â

Immediately Frank phoned Dr. Bates, the family physician, who had already been notified that Fenton Hardy was gravely ill. The doctor promised to arrange for the ambulance to meet the plane.

The brothers then hastened downstairs and entered the house by the rear door. The boysâ mother and their aunt, Gertrude Hardy, were waiting anxiously in the living room.

âDadâs arriving shortly,â Joe announced. âCome on. Weâll all drive to the airport.â

The four Hardys hurried to the family car and Frank took the wheel. For a while they rode in silence, oblivious of the pleasant air, reflecting on the near tragedy which had overtaken Fenton Hardy.

Once a famous detective on the New York City police force, Mr. Hardy now had his own successful investigating practice. He had often been assisted on cases by his sons, who had gained renown for their talent as amateur sleuths. Sam Radley was Mr. Hardyâs able assistant, and Jack Wayne was his private pilot and close friend.

Laura Hardy spoke up. âI had a strong feeling this case would prove unusually dangerous when Fenton agreed to accept it.â

Mr. Hardyâs assignment had been to investigate suspected sabotage on part of a road being built by the Prito Construction Company in the Kentucky wilderness. Mr. Prito was the father of one of the Hardy brothersâ best friends, Tony.

A bridge on which the Pritoâs crew were working had collapsed. The county inspector was accusing the firm of having used faulty material, although this had been ruled out by tests. However, Mr. Prito had discovered that bolts had been removed from supporting steel girders. Inquiries among the workers had shed no light on the identity of the saboteurs.

The detective had flown to Kentucky in his personal plane, piloted by Jack Wayne. But the day after his arrival Mr. Hardy had mysteriously disappeared. Sam Radley had been summoned to help on the case and was to have met his boss for a briefing at the construction site that same day.

When Mr. Hardy did not appear, Sam had gone to the neighboring small town of Boonton, sure that the investigator would soon return. But Fenton Hardy was gone for almost a week.

His family recalled vividly Samâs account of the detective finally stumbling into Boonton, his hands manacled behind his back, gravely ill and delirious. The small local hospital had diagnosed pneumonia, but with baffling complications, and urged that he be returned home immediately.

Sam had reported, too, that no clue had been found to explain who had held Mr. Hardy prisoner, or where. Also, his brief case was missing.

As Frank swung into the parking area of the airport, Joe leaned excitedly out the window.

âThereâs Dadâs plane. Jackâs bringing her in!â

Minutes later the family stood near the ambulance, waiting alongside the apron. The four watched the blue-and-white, single-engine plane glide to a landing and taxi up to the ambulance.

Two white-coated attendants hopped out and joined Frank and Joe as they rushed to the craft. The cabin door opened. Sam Radley poked his head out. âYour dadâs already on a stretcher,â he told the boys.

They leaped aboard. Both gasped at first view of their father. A rugged man, Fenton Hardyâs face normally had a healthy glow. Today he looked pale and drawn, and his eyes were closed. Gently the brothers and Sam lowered the stretcher to the attendants.

Laura Hardy wept softly as her husband was carried toward the ambulance, and Aunt Gertrude tried hard to hold back her own tears.

Joe bent over the stretcher. âDad, can you hear me?â Mr. Hardyâs eyelids fluttered. His lips moved feebly, but no intelligible words came out.

âStill delirious,â said Radley. âHeâs been mumbling like this on and off. I couldnât catch a thing.â

âIf only we could get a few words,â Frank said. âThey might give us a clue to the fiends who did this to Dad.â

The stretcher was placed in the ambulance. The Hardys and Sam looked back to the plane. Jack Wayne, somber-faced, peered out of the cockpit and waved. Then the pilot taxied the craft to its hangar.

It was decided that Frank and Mrs. Hardy would accompany the patient, while Aunt Gertrude, Joe, and Sam would go in the car. Soon the ambulance was speeding toward Bayport.

Joe, at the wheel of the Hardy car, asked Radley, âI didnât notice any plane landing before we left the airfield. You have any idea who was tailing you?â

âNo. The guy was deverâkept a safe distance all the way.â

Joe looked troubled. He was thinking hard. âSam, I have an idea,â he said. âIâll stop home for our tape recorder. We can set it up by Dadâs bed in the hospital, just in case he says something understandable when weâre not there. We need a due desperately.â

âItâs worth a try. Maybe weâll get some answers to vital questions in this mystery. For instance, who masterminded your fatherâs kidnapping? Where was he held? And how did he get back to Boonton, handcuffed and sick the way he was? Somebody must have brought him there, but why?â

âWeâll get to the bottom of this!â Joe vowed. He turned off the highway and headed for the Hardy residence on Elm and High streets.

Aunt Gertrude, usually critical of her nephewsâ detective work, for once agreed.

âOh, Iâd like to get hold of thoseâthose terrible creatures myself!â she declared vehemently. âBut please, Joe, you and Frank be very careful. We donât want you in the hospital, too.â

âBy the way,â Sam asked as they pulled into the driveway, âhave you heard from my wife?â

âYes,â Joe answered. âShe phoned yesterday, asking about you. Sheâs fine.â

Sam and his wife lived in an apartment near the center of town, about half a mile from the Hardys.

Joe hurried to get the tape recorder. He tested it and put on a new tape. He and Sam were about to leave when a taxi screeched to a stop in front of the house. To their amazement, Frank leaped out and rushed inside.

âHey, what happened?â Joe greeted him.

âA clue, our first one!â his brother announced. He reached into a pocket, pulled out an envelope, and held it open to reveal a white, gritty substance.

âWhereâd you find this?â Joe asked quickly.

âIn the cuffs of Dadâs trousers. Come on. Weâll examine this stuff right away.â

The boys and Sam ran up the stairway to the garage lab. First the Hardys studied the white grains under a microscope. âLooks like tiny bits of rock,â Frank observed.

âThis could be limestone,â Joe said. âLetâs run a chemical test.â

As Sam looked on, Frank shook the particles into a flask while Joe filled a beaker with clear limewater, then connected the two containers with glass tubing. Frank next picked up a bottle of dilute hydrochloric acid and poured it onto the grains. Bubbles appeared in the beaker and the limewater turned cloudy, then clear again.

âLimestone it is!â Joe exclaimed. âSam, do you know of any limestone quarries around where you and Dad were in Kentucky?â

âNot offhand. But there are plenty of unusual rock formations. In fact, plans are underway for developing an immense parkâsort of a tourist attractionâfeaturing the peculiar formations.â

âNear the highway construction site?â Frank asked.

âQuite near.â

As the Hardys put away the apparatus, the extension phone rang. Frank answered. âHello.... What was that? ... I canât understand you.... Wait a minute.â He turned to Sam. âSounds like your wife, but sheâs awfully upset.â

Sam grabbed the phone. âHello? ... Ethel?â A frightened look came into his eyes. âIâll be right over. Try to keep calm!â

He wheeled about to face the boys. âSomethingâs happened to my wife. Letâs hurry!â

The three pounded downstairs. While Joe sped into the house to pick up the tape recorder, Frank and Sam ran to the car.

âAunt Gertrude!â Frank exclaimed, âWe have to rush over to Samâs. Somethingâs wrong. Wait here at the house, and donât let anybody in until we return!â

Miss Hardy got out of the car. âVery well. But what about Mr. Kenfield? Heâs coming to inspect the roof today.â

âOkay. But he probably wonât have to come into the house. Heâll use a ladder to get to the roof.â

The Hardys and Sam sped to the Radley apartment. It was located on the second floor. The door was slightly ajar and Radley burst in, the boys at his heels. âGood grief!â Sam cried out.

His wife was lying on the living-room floor, her feet bound together and her hands secured in front of her with stout twine.

âThis could be limestone,â Joe said

âSam! Sam!â she sobbed. âOh, Iâm so glad youâre here!â

Frank whipped out his pocketknife and cut the bonds. Mrs. Radley, still trembling with fright, was helped to her feet. Joe hastened to get her a glass of water, while Sam insisted she rest in an easy chair. When Mrs. Radley had regained her composure, she told them what happened.

âIâd been out shopping for about an hour. When I returned, I was surprised to find our door unlocked, but thought Iâd absent-mindedly left the catch off. I went inside and almost fainted when I saw a strange man in the living room.â

The intruder had clapped a hand over her mouth, bound her, and warned her to make no outcry.

Frank wondered whether the prowler had anything to do with the Hardysâ case. âWhat did he look like?â Frank asked.

âHe was tall, dark andâOh, I canât tell you any more! I was so frightened.â

âHe was here for a purpose, thatâs sure,â Sam said as he inspected the door lock. âItâs been jimmied.â

Nothing seemed to be disturbed in the living room. Then the Hardys accompanied Sam into his study. One drawer of a filing cabinet was partly opened. Radley quickly examined the contents. âNone of these files are missing,â he said, perplexed.

Frank pointed to the top drawer. âHow about that card index?â

Sam pulled out the drawer. âYouâre right! There are a couple of cards sticking up, as if someone had riffled through them.â

With painstaking care, the three sleuths checked the cross index of a long list of criminals which Sam had catalogued.

âYou know thereâs a duplicate set in your dadâs office,â he told the boys.

By this time they had reached the names listed under M. âManderâManningâMatlack. Wait!â said Sam. âIâm missing the run-down card on Milo Matlack.â

âWhoâs Matlack?â

Radley gave a low whistle. âHeâs an ex-convict, a dangerous characterâone of the worst!â

CHAPTER II

A Midnight Alarm

âIF Matlackâs the bird we want, weâll clip his wings,â said Joe, âno matter how tough he is!â

âLetâs not jump to conclusions,â cautioned Frank.

Sam went through the rest of the file. No other card was missing.

âWeâll check the duplicate file right after we visit Dad,â Frank said.

Satisfied that Mrs. Radley was feeling all right, the Hardys left the couple. âWeâll keep in touch with you about developments, Sam,â Frank promised.

The boys hastened outside to their car and soon reached the hospitalâs parking lot.

âI hope Dad is better,â Joe murmured as they rode the elevator to the third floor. But he and Frank found Mr. Hardyâs condition the same. Mrs. Hardy was quietly talking with Dr. Bates. Both were looking gravely at the detective, who was breathing irregularly and still in delirium.

Noting Frankâs and Joeâs alarmed expressions, the medic assured them everything was under control. âYour dad is very ill, of course. The pneumonia we can treat, but weâll have to conduct further tests to determine the exact cause of his prolonged loss of memory.â

âHow did he ever catch pneumonia?â asked Joe, stepping close to the bedside and looking down at his fatherâs face, now flushed with fever.

âPossibly through extreme mistreatment,â the doctor said. âMr. Hardy might have been kept in a dark, damp place without food and sufficient water.â

Frank set his jaw grimly. âCouldâve been an underground prison,â he declared, âwhich might explain the limestone in Dadâs trouser cuffs.â

Just then Mr. Hardy turned his head on the pillow. His eyes were still closed. He mumbled, but as before, the words were unintelligible.

Mrs. Hardy sighed. âHeâs been doing that all the time Iâve been here,â she told her sons.

Joe placed the tape recorder on the night table next to his fatherâs bed, and explained what he had in mind. Frank plugged in the machine. Just then a pleasant-looking nurse came into the room. She introduced herself as Miss Tice.

âIâll be on night duty here,â she said. âIs there anything special youâd like me to do?â

âYes, please.â Frank showed her how to turn off the recorder and change the tape. He left a spare reel on the table.

âWhen you put on the new tape,â Frank went on, âplease put the used one in the drawer so it wonât be damaged.â

The boys and their mother were assured by the doctor that Mr. Hardy would respond to treatment.

âYour husband needs complete rest, Mrs. Hardy,â the physician added. âIf there should be any change, weâll call you immediately.â

Joe switched on the recorder, then the three Hardys left the hospital and drove home. They found Aunt Gertrude setting the table for supper and gave her the latest report on her brotherâs condition.

âSee anybody prowling around while we were gone?â Joe asked.

âGoodness no!â Miss Hardy said tartly. âDidnât we have enough worry for one day?â Then she added, âMr. Kenfield was here, of course. I heard his ladder being propped against the side of the house, and I saw his truck parked in front.â

Frank only half heard his auntâs words. His memory was suddenly jogged by another thought. âJoe! Letâs check Dadâs files!â

Aunt Gertrude fixed her nephews with a stern gaze. âDonât be late for supper!â she ordered. âWeâre having lamb stew and I donât want it to get cold!â

âAunty,â Joe said, âweâre never late for lamb stew.â

He winked at his brother and followed him upstairs to Mr. Hardyâs study on the second floor. From a secret compartment under a desk drawer, Frank withdrew the key to his fatherâs extensive files.

Quickly they began looking through the cross index and the individual run-down cards.

âNothingâs been touched so far,â Joe observed as Frank deftly separated the cards.

âYes, everythingâs okay through L,â Frank said, then started on the Mâs.

A moment later Joe exclaimed, âHey! Thereâs no card for Milo Matlack.â

Frank grinned. âDonât get excited. Dad took the card himself and left this memo.â

A slip of paper with Mr. Hardyâs handwriting bore the notation that the detective had taken not only the card, but also the complete dossier on the ex-convict with him to Kentucky.

âI knew it!â Joe burst out. âMatlackâs our man beyond a shadow of doubt.â

âGuess youâre right,â Frank conceded. âSo, if we can find Milo Matlack, we may crack this case. Something tells me itâll be no cinch.â

The brother sleuths had already solved a number of baffling mysteries, from locating The Tower Treasure to recently uncovering the secret of The Haunted Fort.

As Frank locked the files, Joe grabbed the telephone and dialed Radleyâs number. Sam answered. Joe first inquired about Mrs. Radley.

âSheâs feeling better. But no leads yet to the intruder.â

âSam, weâre hot on a trail!â Joe told the operative of Mr. Hardyâs memo, then asked if Sam could describe Matlack and give some of the criminalâs history.

âI canât recall much detail,â Radley replied. âBut I do remember that Milo has gray hair.â

âWhere are we likely to find him?â

âPossibly in New York City, his old home.â

âThen thatâs where weâll go!â Joe declared. Sam promised to round up all the information he could on the former jailbird. Joe thanked him and hung up.

âBoys! Supper!â Miss Hardy called up.

The boys quickly washed, then hurried to the dining room. Joe held a chair for his mother, and Frank helped Aunt Gertrude place a steaming tureen of stew on the table. As Mrs. Hardy served, her sons told the women about the latest exciting developments in their fatherâs mystery.

âThere are two things Joe and I have to do!â said Frank. âCapture Milo Matlack and make him pay for what he did to Dad, and second, unearth the real story behind the bridge collapse.â

âThe police should handle such aâa fiend,â Aunt Gertrude stated.

âThe police can help us,â Joe said, âbut we want to collar Matlack ourselves.â

Although fearful for her sonsâ safety, Mrs. Hardy was proud of their courage and ability. Quietly she advised them to exercise the utmost caution.

âDonât worry, Mother,â said Frank. âWe will.â

After supper the boys went to their fatherâs study and discussed the mystery until bedtime. Before retiring, Frank telephoned the hospital and learned that Mr. Hardyâs condition was about the same.

Late that night the boys were jolted from a deep sleep by the shrill jangling of the telephone. Frank switched on the bedside lamp and dashed to pick up the hall extension. Joe followed.

The caller was Miss Tice, the night nurse. âYouâre to come right over to the hospital,â she told Frank in a tense voice.

Frankâs heart sank. âYou mean the whole family?â

âCertainly not,â replied the nurse. âJust you and your brother.â

âWeâll be there,â said Frank and hung up. âHurry, Joe! Something must have happened!â

Hastily the boys changed from pajamas to street clothes.

They were grimly silent as they whizzed through the streets to the hospital. There they took the elevator to the third floor. It seemed forever until they reached it and the door slid open. The boys rushed to the nursesâ station.

âIs DadâFenton Hardyâs condition worse?â Frank asked the nurse in charge. âIs that why Nurse Tice called?â

âMercy, no!â she whispered. âIf anything, your father is slightly improved.â

Although vastly relieved, Joe said wryly, âWe sure had the daylights scared out of us!â

âIâm afraid weâve had the daylights scared out of us, too,â the nurse replied. âMiss Tice will explain.â

On tiptoe, Frank and Joe ran down the corridor. Nurse Tice, red-faced and distraught, met them outside Mr. Hardyâs room.

âWhy didnât you post a guard here if you expected trouble?â she asked indignantly.

Frank gulped. âTrouble? Did somebody try to hurt Dad?â

âNo, not that.â

âTell us what did happen!â Joe said impatiently.

âA man, dressed as an intern, sneaked into your fatherâs room, thatâs what!â said the nurse.

Frank drew a deep breath. âAnd then?â

âI was coming back after my coffee break,â Miss Tice continued, âand I saw this man in white removing the tape from the recorder. I was so surprised I cried out and he came rushing at me. I tried to stop him, but he got away.â The nurse looked puzzled. âWhy anybody would steal a tape with just mumbling on it is a mystery to me!â

CHAPTER III

Who Is Felix?

FRANK and Joe stared at each other in dismay. âWe should have had someone guarding Dad,â Frank said glumly.

âWell, there are two police officers here now,â Nurse Tice replied.

âPolicemen?â queried Joe. âWhere?â

âTheyâre searching the building. The night supervisor phoned headquarters as soon as I reported seeing that thief.â

The Hardy boys had hoped to handle this case mostly by themselves. Now the police already had been called in. Sensing their concern, Miss Tice became apologetic. âI donât usually flare up like that,â she said. âBut it was an unnerving experience.â

âWeâre sorry you had such a scare,â said Joe. âIâd sure like to get my hands on that phony.â

âAt least,â Miss Tice remarked, âyou still have the tape.â

âWhat?â Frank exclaimed. âI thought the thief got away with it.â

âI forgot to mention Iâd changed the tape.â The nurse opened the night-table drawer and pulled out the first tape.

âThanks a million,â Joe said. âWeâll take the recorder and play the tape when we get home.â

When the nurse had checked Mr. Hardyâs pulse and respiration, Frank asked if she could describe the thief.

âThe man was tall,â she said, âwith jet-black hair and a mustache.â The impostor, she added, had worn a mask which she had almost torn off during her tussle with him. âIf Iâd known Judo,â added Miss Tice, âI might have caught him!â

The boys exchanged glances. Except for the mustache, this description resembled that of the intruder at Radleyâs apartment!

At the sound of brisk footsteps in the corridor, the nurse and the Hardys left the room. Outside, they met Chief Ezra Collig of the Bayport Police Department, followed by a patrolman, who held a rumpled white jacket in his hands.

âHello, Frank, Joe,â the husky, keen-eyed chief said. Collig was an old friend of the Hardy detectives. âWhen I learned your father was here, I wanted to investigate this matter myself.â

Joe looked at the jacket. âIs that the one the thief wore?â

âYes,â replied the chief. âWe found it near the first-floor fire exit.â Colligâs eyes narrowed. âAre you sure, Miss Tice, there was nothing else stolen from this room? Like hypodermic syringes or sedatives?â

âPositive,â the nurse assured him.

Frank spoke up. âJoe and I hope to solve this mystery on our own, Chief, but weâd like to brief you on it.â

The boys gave the officer a concise account, ending with their plan for possibly picking up a clue on tape.

âGood idea,â the chief said. âIâll do my best to help you. At least we can have an alert sent out for anyone resembling the intruder. Iâm posting a guard on this floor, and also will have this jacket analyzed in our lab.â

âThanks, Chief. Thatâs swell,â said Frank.

When the police had gone, Frank asked the nurse, âDid you have much of a tussle with the thief?â

âNo. When I grabbed his mask, he pushed me aside and ran.â

âWould you mind showing me your fingernails?â Frank requested.

The woman held out her hands. Using a pocket flashlight, Frank carefully scrutinized both hands. Suddenly he said, âHereâs somethingâa wisp of black hair!â He pointed to the nurseâs right forefinger.

âWhy, I never noticed it!â she exclaimed.

Miss Tice removed the tiny hair, which Frank folded in a sheet of white paper and put in his slacks pocket.

The young sleuths took the recorder, thanked the nurse for her cooperation, and left the room. Outside Mr. Hardyâs door was a patrolman whom the boys knew. He assured them, âNo sneak thief will get by Tim Callahan.â

The Hardys grinned. âI believe it, Mike,â said Joe.

As soon as they arrived home, Frank and Joe went directly to their lab. Frank was first to study the strand of hair under a powerful microscope. âJoe! Take a look!â

His brother did so. âSay! That hairâs gray near the roots. Itâs dyed black!â Joe was exuberant. âMatlackâs for sure. I bet the mustache is phony too.â

Both boys were exhilarated by the thrill of their discovery. Now for the tape. Did it, too, hold a valuable clue?

Soon the tape was revolving on the machine, and although Frank had turned the volume up full, there were great stretches of silence. These were interspersed by Mr. Hardyâs mumbling, which was indecipherableâexcept one word that came through with relative clarity.

âWhatâs that, Joe? Something like âlicksâ? Iâll play it back.â The strange word, or part of a word, came over three times.

Joe listened intently. âSounds to me like Felix,â he said.

âCould be. Perhaps Felix is a henchman of Matlackâs.â Frank shut off the machine and Joe telephoned police headquarters. Chief Collig was still there.

âChief,â said Joe, âdo you know of any underworld character named Felix? We think thatâs a word which came over on the tape.â

Collig said this did not ring a bell, but he would check his files thoroughly. âIâll let you know.â

When Frank and Joe returned to the house, they quietly went into the kitchen and made cocoa. As they drank, the brothers discussed the nightâs events. Suddenly Joe put down his cup. âFrank! In all the excitement we forgot to check the airport for the plane that tailed Jack!â

Frank immediately telephoned Bayport Airport, and learned that one other plane from Kentucky, an air taxi out of Louisville, had asked for landing permission the previous afternoon. It had taken off a short while ago.

âJoe, that Kentucky pilot must have been the one who tailed Dadâs plane!â Frank exclaimed. âWish we couldâve nabbed him.â

âWhere is he headed?â Joe asked.

âLa Guardia Airport in New York.â Because it was too late for the Hardy boys to do anything further, they tumbled into bed. Early the next morning Aunt Gertrude summoned them to breakfast. Although the bacon and scrambled eggs were delicious, Frank and Joe hardly tasted the food. Directly after the meal, the boys rushed to the telephone in their fatherâs study.

It seemed an interminable wait, but Frank finally contacted an official at La Guardia. The man said that an air taxi from Louisville had landed early that morning and discharged its only passenger.

âIs the plane still there?â asked Frank.

âYes,â was the reply. âThe pilot is checking weather reports. Would you like to speak with him?â

Frankâs eyes brightened. âCertainly would!â

The pilot, who proved to be an accredited flier, reported that his passenger, a dark-haired, tall man with a mustache, had carried a large roll of hundred-dollar bills, from which he had peeled the fee for the chartered flight.

Upon hearing that he had flown a suspected criminal, the pilot whistled. âI wondered why he seemed so nervous about the plane ahead. Kept telling me not to get too closeâjust an act, I guess.â

Frank then asked, âDo you happen to know where he was heading?â

âAfraid not. Just that he was going to take a taxi into the city.â

Frank thanked the flier and hung up. When he told Joe what had happened, his brother said, âWell, at least, if the ratâs in New York City, maybe he wonât be pestering Dad.â

The boys went downstairs. Suddenly they heard a series of loud bangs from outside. Aunt Gertrude ran out of the kitchen and gave a startled squeak. But her nephews grinned, quickly recognizing the source of the noise.

âThatâs only Chetâs jalopy, backfiring,â Joe said.

This conclusion was verified by a cheerful whistle as Chet Morton came through the back door. Frank and Joe entered the kitchen just as Chet, their best pal, plopped his ample frame into a chair. A longing look came over his round, freckled face.

âOhâoh,â Joe said knowingly. âGuess whoâs ready for a second breakfast?â

Chet was known far and wide for his never-failing and huge appetite. âWe-ll, I could use a snack.â

âHumph!â Aunt Gertrude sniffed. âAfter you scared us half to death with that noisy jalopy?â

âThat backfire is getting better, isnât it?â Chet said good-naturedly.

Soon he was enjoying a thick bacon-and-egg sandwich on toast and a glass of milk, served by Miss Hardy.

âSure is a beautiful day, fellows,â he said, between bites. âWhat say we take a ride on Barmet Bay in your motorboat?â

âNot a chance,â said Frank.

âWhy not? By the way, have you heard from your father?â

The brothers related everything that had happened. Chet was shocked to hear of Mr. Hardyâs illness. âBoy! He must have run into a gang of dangerous criminals.â

Joe could not resist saying, âIn fact, that hospital prowler might turn up around our neighborhood.â

Chet swallowed hard. âW-what? Areâare you going after him?â

âSure thing,â Frank said. âYou want to help us?â

Chet groaned. âCount me out! This is vacation, remember?â

Fond of fun, opposed to hard work, and inclined to back away from danger, Chet nonetheless was staunchly loyal to his pals. When necessary, he pitched in with two-fisted determination to assist Frank and Joe in threatening situations.

Now the chubby boy looked up sheepishly from his second glass of milk. âYou know, if you really need me, Iâllââ

âThatâs the spirit!â Joe grinned. âWeâll expect you to come on the run if we call for help.â

âIâll be available.â

Excusing themselves, Frank and Joe once more hastened to the study. First they checked with Chief Collig. There were no clues on the internâs jacket, and no Felix in the police files. Then Joe phoned Sam Radley and listened with raised eyebrows as the operative talked.

âSam, youâve really been busy! Iâll take that down.â Joe wrote quickly on a note pad. When he hung up the phone, he told his brother, âSam contacted a New York prison where Matlack served time. He was released a year ago, and went to live in New York with a widowed sister. I have her address.â

âWhat a break!â Frank exclaimed. âAll clues point to Manhattanâso thatâs our next stop.â

He called Jack Wayne, who agreed to fly the boys to La Guardia early that afternoon. When the brothers announced their plan, Aunt Gertrude objected. âYou canât just leave us,â she said. âI know the police are protecting your father, but what about your mother and me?â

âI can help,â Chet offered.

âGreat!â said Frank. âMaybe Biff, Tony, and Phil can, too. Weâll call them for a meeting.â

Within an hour the three boys had joined Frank, Joe, and Chet in Mr. Hardyâs study. Biff Hooper was a well-built, six-footer whose favorite pastime was boxing. Tony Prito, slightly shorter, was handsome with an olive complexion and dark eyes. Phil Cohen, slender and agile, had an easy-going manner. His friends admired his great talent for drawing and painting.

âI sure feel terrible about what happened to your dad,â said Tony. âEspecially since he was working on this case for my father. Tell us what to do.â

Frank and Joe outlined their plans. All four of the Hardysâ chums would take turns helping Radley guard their home, and if necessary, relieve Colligâs guards at the hospital.

âI hope you nail this guy Matlack,â said Biff. âGood luck!â

After lunch and a visit to see their father, Frank and Joe drove to the airport. They left their car in the parking lot and hurried to meet Jack at the plane. Twenty minutes later the boys were looking down on the green countryside five thousand feet below, as Jack headed for New York.

The brothers were licensed pilots, and took turns at the wheel. But as they neared the metropolis, Wayne resumed control, contacted La Guardia tower for instructions, and soon brought the plane in.

Grabbing their suitcases, the Hardys thanked Jack for the lift and hopped out.

âSo long,â called the lean young pilot. âCall me if you need me.â

âWill do!â The brothers hurried through the terminal, hailed a taxi, and headed directly for the address which Radley had given them. Presently they reached a dingy section of downtown Manhattan, and soon pulled up in front of a dilapidated, multiple-family dwelling.

âThis is it, Number 47,â said Frank. He paid the taximan and the boys got out.

The Hardys stood for a few minutes, noting the various details of the structureâwindows, doorway, and fire escape. âShall we make inquiries now?â asked Joe.

âNot yet. We better find a place to stay. Thereâs a hotel down the street. Doesnât look like much, but at least itâs close.â

The young sleuths sauntered to the shabby hotel and mounted a short flight of steps which led into the dimly lighted lobby.

The brothers grimaced at the stale musty odor which greeted them. They registered at the desk and were given a key to Room 306.

âCash and carry,â said the clerk, a prune-faced individual with thinning hair. âPay now and carry your own bags.â

âGreat welcome,â Joe whispered wryly as they climbed the creaking stairway.

Frank and Joeâs room was no more than they expected: peeling wallpaper, one bare ceiling light bulb, a sagging bed, and two lumpy chairs.

They had just finished unpacking when they heard the low growl of a siren outside. The Hardys looked out the window. Parked directly below was a police car, its red toplight spinning.

âWonder whatâs up,â Joe said.

The next instant the door to their room was kicked open with an earsplitting slam!

CHAPTER IV

Attack From Above

STARTLED, Frank and Joe wheeled about to see a dark-suited man standing in the doorway, pointing a revolver in their direction. âStand where you are!â he barked.

âWho are you?â Joe blurted.

âDetective Mulvey, New York Police Department.â

Immediately two uniformed policemen stepped from behind Mulvey. âTurn around and put your hands high against the wall!â The brothers did as they were told and the police searched them. âTheyâre clean,â one said.

âWhatâs this all about?â Frank protested. âWeâre not crooks.â

âIdentify yourselves.â Frank and Joe pulled out their wallets and produced the necessary cards.

âOur father is Fenton Hardy,â Frank said. âHe used to work for the New York Police Department.â

âIâve heard of him. Good cop,â said Mulvey. Then he apologized for the mistake. âBut we have to follow up every tip we get.â

âTip?â Joe asked.

Detective Mulvey said a man had telephoned the police, saying that two dangerous criminals had registered in Room 306 at the hotel.

âSomebody sure has a tail on us,â Joe commented. âWho do you suppose he could be, Frank?â

âBeats me.â

The detective spoke up. âWhoever it is, you obviously have an enemy. This is a rough neighborhood. I advise you to return to Bayport.â

âWeâve got to find a man named Milo Matlack,â Joe said. âDo you know of anybody in this neighborhood by that name?â

The three officers, who had just recently been assigned to cover the area, shook their heads. âBut that doesnât mean a thing,â said the detective. âA lot of the characters around here use aliases.â

After the police left, Frank and Joe flopped down in the decrepit, overstuffed chairs, half angry, half amused.

âWhat a joke!â Joe burst out. âWeâre trying to catch an ex-con and we almost get nabbed instead. I feel as if Iâm in left field without a glove.â

âAt least weâve been alerted,â Frank said. âWeâll be on our guard every second.â

After supper in a nearby restaurant the Hardys decided to turn in early. âTomorrow weâll investigate that house first thing,â said Frank.

As a precaution against prowlers the boys stood guard in four-hour shifts. The night passed uneventfully, however.

After an early breakfast, the boys walked to No. 47. They climbed the steps and rang a rusted bell. Several minutes went by. Finally the door opened just enough to disclose a woman in a faded pink housecoat peering out over the safety chain.

Frank introduced himself and Joe. âWeâd like to talk to you about Milo Matlack, please.â

âMilton who?â

âMiloâMilo Matlack. He lives here with his sister.â

âNever heard of him.â The womanâs eyes, close-set in her pudgy face, regarded the Hardys blankly. She brushed her straggling hair back from her forehead. âYou boys got the wrong place. Ainât nobody with that name lives here, and I know all my tenants.â

âBut did Mr. Matlack live here at one time?â Joe said, growing impatient.

âMaybe yes, maybe no.â The woman was about to close the door when a sudden noise from above made Joe glance up.

âFrank, look out!â he cried out. A metal trash can was hurtling down toward the boys. They leaped aside, but the can grazed Frankâs shoulder, clattered on the steps, and rolled down to the sidewalk.

âLet us in!â Joe demanded. âSomeone on your roof is trying to kill us!â

The safety chain clicked open. The Hardys dashed past the startled woman and ran up four flights of stairs to the roof. They glanced about in all directions.

âOver there.â Frank pointed.

The small, monkeylike figure of a man was poised on the roof edge. He gave a flying leap and landed nimbly atop the next building.

âAfter him!â Joe urged.

Frank and Joe had to spring with all their might to equal the monkey manâs leap across the five-story-high chasm. In doing so, they both sprawled on the tar roof of the adjacent building. By the time the boys had pulled themselves up, the small man had slithered down the fire escape and jumped to the ground.

Long before Frank and Joe had descended the iron ladder, their quarry was out of sight.

âGreat horned toads!â said Frank, rubbing his bruised shoulder. âWho was that nut?â

âJust somebody trying to knock us off,â Joe said angrily, and the boys hastened back to pursue their inquiry. The landlady now stood at the bottom of the front steps, having retrieved the trash can.

âYou hurt?â she asked Frank.

He nudged Joe, then replied, âI hope not, maâam. But that was a close call. I couldâve been killed.â

âYou wonât sue me or nothinâ?â the woman said, wringing her fat hands.

As if debating with himself, Frank did not reply. The woman grew more nervous by the second. Joe now looked her squarely in the eye.

âWe wonât make any trouble for you, if you tell us about Matlack.â

âOh, all right,â she said, unhappily beckoning the boys to step closer. âI donât want nobody to hear what Iâm tellinâ you,â she whispered. âAnd donât you say I told you.â

After Frank and Joe had promised not to betray her confidence, the woman admitted that Matlack and his sister had lived there. âTheyâre gone now,â she added, gesturing with her hands. âI canât tell you nothinâ more.â

âOkay,â Frank said. âThanks.â

The boys walked slowly down the street, conjecturing about the strange actions of the monkey man.

âI bet heâs in cahoots with Matlack,â said Joe.

âItâs possible. Say, now that we know Matlack lived here,â Frank went on, âletâs question some of the other people on the block.â

âOkay.â

They entered what seemed to be primarily a hardware store, but which also contained a jumble of miscellaneous articles.

âBoy, what a junk shop!â Joe murmured as they approached the short, squat man behind the counter. He peered gravely at the Hardys through thick-lensed glasses.

âWeâre looking for a man named Matlack,â Frank said. âWe understand he used to live in this neighborhood. Do you know anything about him?â

The stout man stared unblinkingly at the Hardys, first at Frank, then at Joe, as if sizing them up. Then, suddenly, he broke into raucous laughter.

âCanât you answer our question?â asked Joe, annoyed.

The man stopped laughing. âAre you kiddinâ?â he said gruffly. âIf you guys donât want to buy nothinâ, get out!â

He stalked to the back and disappeared through a doorway. The Hardys shrugged and left.

Joe grumbled, âHe must have had raw meat for breakfast!â

The boys continued down the street. Both were so engrossed in their quest they were unaware that two tough-looking youths were trailing them, until one roughly elbowed Frank.

âMove over!â he snarled. âYou own the whole street?â

âExcuse us,â Frank said calmly.

âOh, excuse us,â the youth echoed mockingly. âHey, Spike! A couple of real polite country boys!â

Joe turned on the pair, but his brother restrained him. âCome on, Joe. Letâs not waste our time. These two are spoiling for trouble.â

The Hardys started on, but the second tough clamped a hand on Joeâs shoulder, spinning him around. This was too much for Joe. He seized his assailant, and with a flying mare sent him over his shoulder. The fellow landed on his back with a grunt. His pal, meanwhile, had tried to grapple with Frank, but his success was no greater. Frank applied a half nelson, until beads of sweat stood out on his opponentâs forehead. Then, with a shove, Frank sent him sprawling. The two thugs, muttering threats, retreated into an alley. The Hardys headed straight toward their hotel.

âListen, Joe,â Frank said, âweâve got to plan some strategy. Weâre getting nowhere in a hurry.â

They were about to mount the steps to the hotelâs front door when a grizzled, gaunt, shifty-eyed man approached them. âOhâoh, this bum wants a handout,â Joe said in a low voice. âHe must be king of the down-and-outers.â

Despite the warm weather, the man wore a long, threadbare overcoat which nearly touched the ground. His brown hair was streaked with gray and slicked back. A dead cigarette dangled from one corner of his mouth.

âWhatcha say boys, whatcha say!â mumbled the man. âHow about a dime for a cup oâ coffee?â

âOh, we might as well,â Joe whispered. âItâll be worth it to get rid of him.â

âWait a minute.â Frank addressed the pan-handler.

âHave you been around this neighborhood long?â

The beggarâs long, sharp nose twitched and his foxy-looking eyes nearly closed with mirth as he said with a chuckle, âLong! Iâll sayâI was born here.â

âThen you must know the people on this block, right?â Frank queried.

âSure do. You lookinâ for somebody special?â

âYes, a man named Milo Matlack.â

Frank and Joe watched closely for the strangerâs reaction. His brows furrowed deeply and his eyes rolled from side to side, as if searching his memory.

âYeah, I know Matlack,â the man finally said.

âCan you tell us where he is?â Joe put in eagerly. âItâs important.â

The tramp rubbed his fingertips over the moth-eaten labels of his coat with evident satisfaction.

âSoâyou wanna know where Milo Matlack is, eh?â

âThatâs the idea,â Frank said somewhat sharply, realizing the man was purposely delaying an answer.

âWell, I can tell you.â The tramp thrust his grizzled chin at Frank. âI can tell youâfor a price!â

CHAPTER V

Dead End

JOE HARDY could barely control his irritation. He opened his mouth to protest, but his brother muttered, âCool it.â

Frank then calmly turned to the man. âWhat is your price, Mr.ââ

âPrince. Mortimer Prince is my name, and my price is a hundred dollars.â

âNo. Thatâs out!â Frank said in disgust, and began to mount the steps.

Mortimer Prince tugged at Frankâs arm. âWe can bargain, canât we?â he said with a shrug. âSo you ainât got a hundred dollars. How about fifty?â

âI wouldnât give you even a dime,â Frank said icily, shrugging off the grimy hand.

âAll right, all right, donât get mad,â the bum said hastily. âTell you whatâIâll settle for some grub.â

âItâs a bargain,â Frank said quickly. âAll you can eat if you tell us where to find Milo Matlack.â

Mortimer Prince grinned cheerily and beckoned the boys to follow him. Halfway down the block he ushered them into a dingy place called âJackâs.â The three took seats at a small round table.

The vagrant blithely ordered six hamburgers and a double plate of baked beans. As he dived into the food, the boys plied him with questions, but Mortimer did not reply.

âCanât talk while Iâm eatinâ,â he mumbled through a mouthful of meat.

The Hardys waited with growing impatience. With a huge sigh of relish, Mortimer swallowed the last of the beans, wiped his mouth on his coat sleeve, then asked the boys for pencil and paper.

âIâll keep my promise,â he said. âIâll show you how to find Matlack.â

Frank produced a pencil and Joe a piece of paper, which the derelict took into his grubby hands. âIâll draw you a map where theâerâtreasure is,â he said.

âYou mean Milo Matlack?â Joe said quizzically.

âYeah, heâs the treasure youâre lookinâ for, ainât he?â

âGo ahead. Write,â Frank said.

The Hardys watched as the pencil moved, outlining a diagram of streets. Mortimer Prince sniffed and rubbed his nose. âLook, you fellows follow the arrow to this place marked X, see? Thatâs where Matlack is.â

âOkay.â Frank folded the map and tucked it in his shirt pocket.

âNow Iâd like some dessert,â Prince said. âThree scoops of ice creamâll do me.â

When he was served, the vagrant ate the ice cream with gusto, but paused occasionally to complain that it was too cold for his teeth. To the Hardysâ great relief, he finished soon and stood up, proffering his hand to the boys. âNo hard feelinâs. Weâre fair anâ square.â

Frank paid the bill, and the young detectives and their strange guest parted company.

âLeapinâ lizards!â Joe exclaimed as he and Frank set off down the street. âThey say you can meet any and all kinds in New York. And boy, I believe it!â

Frank laughed. Then suddenly he wheeled and grasped his brotherâs arm. âJoe, look!â

Reflected in a store window, next to them, was the monkeylike figure of their rooftop assailant! Both boys swung around. The monkey man, on the other side of the street, stood staring at them!

Impulsively Joe dashed across the road. A horn blared. Brakes screeched. A taxicab, bearing down on Joe, stopped a hairbreadth from his flying legs. The driver, red-faced, leaned out the window and shook his fist at Joe.

âYou birdbrain! Thatâs a quick way to get to the graveyard!â

Frank hastened to his brotherâs side, glancing about for the monkey man, but he had disappeared again.

âJoe, next time watch it!â Frank chided him.

âIâll say,â the angry taximan agreed. âGuys like you make it hard for a man tryinâ to earn an honest livinâ.â

âOkay, okay, Iâm sorry,â said Joe. âWeâll give you some business, anyhow.â

The Hardys hopped into the taxi and Frank showed the driver the map drawn by the tramp. âCan you take us to the place marked X?â

âItâs over on Long Island,â the man said. âCost you a fat fare.â

The driver sped off uptown, through a tunnel, and finally emerged onto a broad highway. Presently he turned off and half an hour later slowed down at a small cemetery. To the Hardysâ astonishment, the driver turned into the cemetery entrance, stopped, and pointed to the X on the map.

âThis is it, fellers.â With a wink at Joe and a chuckle, he added, âYou got to the graveyard after all, didnât you?â

Joe smiled weakly at the gruesome joke. Then the boys paid the driver and stepped out.

âHave fun!â The taximan waved and roared off.

âFor Peteâs sake!â Joe fumed. âI had a feeling that Mortimer would trick us.â

âI wouldnât say he did,â Frank replied. âSure, this is a cemetery, but maybe Matlack works here as a gardener or gravedigger.â

They approached a small brown building marked âOffice.â The door was ajar and the boys stepped inside. Behind a desk sat a portly man with a fringe of white hair like a halo about his head, bushy eyebrows, and a hooked nose which reminded the Hardys of the well-known puppet character, Punch.

âAre you boys looking for a relative?â the man asked solicitously. âIâm the superintendent here.â

âNot exactly,â Frank replied, barely smothering a smile.

âWeâre looking for Mr. Milo Matlack,â Joe spoke up âHave we come to the right place?â

âIndeed you have. Our groundskeeper can show you.â

He led the boys outside and pointed across the gravel lane. A man in overalls was pruning a row of shrubbery. Before the Hardys could walk over, a funeral cortege drove slowly through the entrance gates.

âSorry,â said the superintendent, âguess you fellows will have to wait.â He excused himself and re-entered the office.

The procession was a long one and the Hardys counted fifteen limousines as they slowly drove past. Then the boys hastened across to the groundsman. He readily agreed to take them to Milo Matlack. The trio walked along the gravel lane to the rear of the cemetery. The boysâ guide paused at a low, flat area.

Frank and Joe looked about. They could see nobody.

âWhereâs Matlack?â asked Joe.

âMaybe heâs eating lunch,â Frank said.

This remark brought a look of shocked disbelief to the face of the groundskeeper.

âL-lunch?â he quavered.

Puzzled, the boys followed him in silence to a grave of comparatively recent origin. Frank and Joe bent down to examine the headstone. The brothers sucked in their breath sharply and Frank gasped out, âDead! Milo Matlackâdead!â

CHAPTER VI

An Insulting Warning

THE Hardysâ prime suspect dead! Frank and Joe looked at each other, their mouths agape with bewilderment.

Noting the boysâ queer expressions, the workman asked, âWere you friends of the deceased?â

âOh, no,â Joe replied. âMilo Matlack was aââ

âYes, yes, I know,â the man interrupted. âBut believe me, Milo repented for his crimes. He became very religious while in prison. Was a handyman here, very diligent worker, too.â

The brothers thanked the groundskeeper for his trouble and returned to the office. Here Joe asked the manager if Matlack had met his death at the hands of old gangland enemies.

âNo,â was the reply. The superintendent explained that Milo had become ill soon after the death of his sister and had passed away quietly one night.

âBad ticker, I believe,â the superintendent said, thumping his chest. âI think his heart just plumb gave out.â

Outside the cemetery grounds, the Hardys looked at each other sheepishly, their hands thrust deep in their pockets.

âWellâMortimer Prince must be doubled up laughing at us,â Joe said bitterly. âFor this joke we bought him lunch!â

Frank tried to sound cheerful. âI realize our deductions have been knocked out of orbit, but at least we know Matlackâs off our list.â

âI feel like a goof,â Joe admitted. âHere we tackle a case for Dad, and weâve come across nothing but dead ends.â

âIf we donât get on the ball pretty soon,â Frank remarked, âweâll be low sleuths on the totem pole!â

The Hardys decided to walk for a while before returning to Manhattan. As they strode briskly along, they reviewed every aspect of the mystery. If Matlack was not their man, why was his record stolen from Radley? And why had Fenton Hardy taken Matlackâs files with him to Kentucky?

âThe answers probably are in Dadâs missing brief case,â Frank surmised. âMaybe his dossier on Matlack would help to solve the puzzle.â

âYouâre right. But that brief case could be any where in or out of Kentucky right now.â

For the next ten minutes the brothers walked along in silence. Then Frank said, âOne thing is certain. Dadâs enemies have a super-intelligence system. They didnât waste a minute picking up our trail, and seem to know everything weâve planned at home or in New York.â

âWhich means,â Joe said, âthat monkey man is one of the gang.â He suggested that they return to Bayport. âIf we can track down their spy network there,â Joe added, âit might put us on the right trail.â

Frank hailed a passing taxi, and after a speedy ride, the driver let them out in front of their hotel. Frank paid the fare and turned to his brother.

âLetâs case this block first!â

âYouâre right! That monkey man might still be spying on us.â

The boys separated, each sauntering along opposite sides of the street. As inconspicuously as possible, they surveyed the rooftops, and carefully watched for any suspicious motion behind the dirt-streaked windows.

Joe was passing the house where Matlack had lived, when the front door opened. Out stepped the slovenly landlady, still wearing the pink housecoat. She held a broom in her hands and began to sweep the steps. Joe bounded up to her and Frank followed.

âMilo Matlackâs dead. Why didnât you tell us?â Joe asked.

Instead of replying, the woman scurried into the house and locked the door.

âBoy, sheâs really scared,â Frank declared. âSomebody has threatened her to keep quiet.â

âBut whyâif Matlack is out of the picture?â

âTo keep us on the wrong track!â

Frank and Joe walked across the street and posted themselves in the doorway of a vacant store in case any suspicious person showed up at No. 47. Nothing happened, however, and the landlady did not reappear. The boys also kept an eye out for the vagrant who had tricked them, but the grubby drifter was not to be seen among the passers-by.

Finally they returned to the hotel. The desk clerk handed Frank the room key. âYou two check ing out? Otherwise youâll owe us for another day.â

âWeâre leaving in fifteen minutes.â

In their musty room the Hardys threw the few possessions they had brought into their overnight bags. Joe said to himself, âShaving kit, toothpasteââ His mental check stopped suddenly when he picked up his red-handled toothbrush from the side of the wash basin. A white paper was wrapped around it, held securely by an elastic band.

âFrank, look at this!â Joe slipped off the elastic and opened the paper. Printed on it in crude letters was âWarningâBayport is for Brats.â It was signed with an odd-looking M with three spiral loops.

Frank gritted his teeth. âIf Matlack werenât dead, Iâd swear he left this warning.â

âItâs a dirty insult! Bayport for Brats, eh?â Joe exploded. âWeâll show them.â

The brothers quickly finished packing, hastened downstairs with their bags, and queried the desk clerk. He denied knowledge of the toothbrush warning. A silly grin came over his face. âSay, maybe some joker did it before you left home.â

The Hardys made no comment. Handing over the door key, they left.

âThat was a bright theory!â Joe said sarcastically as the two walked away from the hotel.

Frank stopped at the first public telephone booth and contacted Jack Wayne. The pilot told them the plane was in readiness and that he would take off immediately to meet them at La Guardia. Exactly on schedule Jack set down the Hardy plane at the airfield and the boys climbed into the cabin.

The flight to Bayport was smooth and fast. From the airport, the young sleuths drove directly to the hospital. It was past visiting hours, but they were allowed to look in briefly on Mr. Hardy. Much to Frank and Joeâs relief, they found their father slightly improved, but as yet unable to talk clearly.

Back home, Joe called Sam Radley and told of their experiences in New York. He was surprised to learn that Matlack was dead.

âThis mystery is a real puzzler,â Sam remarked. âAt least you two found out somebodyâs worried by your sleuthing.â

Sam said no further clues had turned up locally to the prowlerâs identity. Then the Hardys checked with their pals. None of the four had detected anyone suspicious lurking near the hospital or the Hardy house.

The following morning Frank and Joe discussed what their next move should be. From the living room came assorted thumps and clicking noises. Aunt Gertrude was assembling the vacuum cleaner with her usual vigor.

âGoodness gracious, Gertrude!â came Mrs. Hardyâs voice. âWe cleaned thoroughly just a few days ago!â

The boys grinned and went into the living room. Joe squinted his eyes, as if inspecting the room. âAunty, relax, thereâs not a cobweb in sight!â

Aunt Gertrude pursed her lips. âDonât be funny,â she said tartly. âThere happens to be a spot on the ceiling in one corner of your fatherâs study.â With an accusing look at her nephews, she added, âYou and your friends were the last to use it.â

âWow!â Joe said. âAunty, Iâll bet you could spot a speck of dust ten miles away. Better be careful, though, it might be a beetle!â

âHumph!â Aunt Gertrude gathered her equipment and carried it up the carpeted stairs.

Suddenly an electrifying thought flashed through Frankâs brain. He ran upstairs. Aunt Gertrude was about to enter the detectiveâs study when Frank grabbed her. The startled woman gasped.

âWhatâ?â was all she could get out, because Frank clapped a hand over her mouth and dragged his flabbergasted aunt into the hall.

CHAPTER VII

Bug Bait

GERTRUDE HARDYâS eyes bulged with fright as Frank kept a hand clapped over her mouth and half carried her down the stairway into the living room.

âGood night!â exclaimed Joe. âWhatââ

âSh, sh!â Frank whispered frantically. âDonât make a sound.â He released his aunt and led the trembling woman into the kitchen. The others followed.

Mrs. Hardy spoke first. âWhat on earth are you up to, Frank?â

âI know,â Aunt Gertrude said tartly as she smoothed her disheveled hair and set her spectacles straight. âFrank has gone stark raving mad, thatâs what!â She glared at her elder nephew.

âIâm sorry, Aunty,â Frank said soothingly. âYou seeâI think that dirt spot on the ceiling youâre talking about is a bug.â

âOh! It really is a beetle! Ugh!â

âNot that kind of bug,â Frank went on with a smile. â âBugâ is slang for a hidden microphone.â

âSo thatâs how the crooks knew all about our plans!â Joe whispered hoarsely.

âBut that seems impossible!â Mrs. Hardy said. âNo outsider has been here recently!â

âExcept Mr. Kenfield,â Aunt Gertrude said. She had calmed down, but there was a look of deep concern on her face.

âHmm. You said you heard his ladder against the house,â Frank reflected. âJoe, letâs go take a look at that ceiling spot.â

After cautioning the two women to keep their voices low, Frank and Joe kicked off their shoes and padded up the stairs. They went into the study and looked at the speck. No larger in circumference than a pencil, it protruded an eighth of an inch from the ceiling, so close to the corner that it might not ordinarily have been seen.

Frank put his finger to his lips and beckoned Joe out into the hall. There he whispered into his brotherâs ear, âItâs a listening device all right. The transmitter must have been installed in our attic.â

Silently Frank opened the door to the attic stairway, and the boys tiptoed up. One window was opened halfway, and near it the Hardys spotted a small radio transmitter, inserted between two floorboards. Impulsively Joe reached down to yank it out, but Frank restrained him.

Retracing their steps, the boys hastened back to the kitchen.

âWell, what kind of beetle is it?â Aunt Gertrude asked.

âThe big-eared type,â Joe replied. He quickly reached for the wall phone extension and called Mr. Kenfield. He asked the roofer to come over immediately.

In about ten minutes the roofer parked his truck in the front of the house. Mr. Kenfield, short and portly, was wearing his work clothes.

âHello, Frank, Joe,â he said as the boys stepped outside to meet him. âI suppose itâs the garage roof you want me to look over, right?â

âNo,â Joe said. âWeâd like to ask you some questions.â

âShoot.â

The boysâ first query was whether or not the roofer had gone into the attic. He said No; that he had examined the roof from the outside only. âBut the electrical inspector,â Mr. Kenfield continued, âwent into your attic.â

âWho?â asked Frank.

âAn electrical inspector. He said you had some rewiring done, and heâd been called to look it over.â

The brothers exchanged glances. This was news to them!

âHow did he get in?â Joe queried.

âAsked if he could use my ladder. It was okay with me. You know Iâm willing to oblige.â

âCan you describe this fellow for us?â Frank asked.

âWhy, sure. He was short, thin, kind of bandy-legged and agile. You shouldâve seen him zip up that ladder! Like aââ

âLike a monkey?â Joe put in.

âYes, sure, thatâs it! I was going to say monkey myself, but I didnât want to insult him if heâs a friend of yours.â

Joe could not help smiling. âHeâs not.â

Frank concluded that the roofer was not to blame. He had had no reason to suspect the âinspectorâ was a fraud.

âThanks a lot, Mr. Kenfield,â Frank said. âThatâs all we wanted to know.â

âGlad to help, any time.â

As soon as the roofer had left, Frank exclaimed, âJoe, now we have a chance to turn the tables! Weâll âconferâ in Dadâs study and feed the bug false information.â

âGreat!â Joe said with enthusiasm.

âThat way we can tell if the mikeâs still in operation, and even lead the crooks on a wild-goose chase,â Frank added.

First the boys told their mother and Aunt Gertrude what they had learned. âSo, if you see the monkey man anywhere around, call us right away,â Frank said. âAnd if weâre not here, notify Chief Collig.â

Aunt Gertrude shuddered. âFirst bugs, now a monkey! Oh dear!â

Frank and Joe put their plan into operation. They walked up the stairs noisily and entered their fatherâs study, chatting loudly.

âWell, weâve got the dope on them,â Frank said. âLetâs fly down to Kentucky.â

âRight away?â Joe asked. He looked up toward the microphone and winked at his brother.

âYou bet. We can get ready in a jiffy.â Frank made the telephone clatter as he lifted it from its cradle. Then, pressing the button down, he dialed and feigned talking with their pilot.

âJack Wayne? ... This is Frank Hardy. Get her fueled up. Weâre taking off for Kentucky this afternoon.â

Frank hung up with a noise that was sure to be picked up by the bug, then added, âCome on, Joe. Weâll give those crooks a hard time.â

The boys confided in Mrs. Hardy what they had done and Frank told her, âWeâre going out to Chetâs. If Jack should phone, please have him buzz us there.â

âAll right. I hope your ruse works.â

The Mortons lived on a farm. The rambling homestead, surrounded by rolling countryside, was a favorite haunt of the Hardy boys. The foremost attraction was Iola Morton, Chetâs dark-haired sister, whom Joe regarded as his best girl. Her friend Callie Shaw, a slender, blond, lithe-some girl, was often at the farm, which suited Frank fine since Callie was his favorite date.

Today, as they pulled up to the house, Frank beamed. âThereâs Callieâs car.â

Joeâs face lit up. âThat means Iolaâs home. Weâre both in luck.â

The Hardys hopped out and looked around for their friends. Suddenly they heard a dull clunk from behind the barn, followed by several giggles. âOh, Chet, that was marvelous!â came Callieâs voice.

âWonder what Chetâs up to now,â Joe said.

He and Frank trotted around a henhouse and reached the rear of the barn in time to see Chet, in a bulky sweatshirt, bend down to pick up a heavy metal ball. The two girls sat in the grass, their backs propped against the barn wall. Seeing Frank and Joe, they immediately jumped up.

âHi!â dark-eyed Iola called gaily. âYouâre just in time to see the exhibition of the year, by no less than my brother!â

âAw, cut it out,â said Chet.

âNo, really,â Callie insisted in mock seriousness. âChet, you are destined to be a fabulous shot-putter.â

The Hardys stood grinning. From time to time their stout friend would plunge enthusiastically into a new sport or hobby. As a rule, the new interest was short-lived.

Frank and Joe flopped down beside the girls. âCâmon, muscles.â Joe urged. âLetâs see you hurl.â

With deliberation, Chet walked back to a circle he had marked out on the grass. He picked up a book lying there and studied it intently. The title was Proper Methods for Putting the Shot.

âIâm glad to see you concentrating so hard, Chet old boy,â Joe needled.

âKid all you want,â retorted Chet, mopping a trickle of sweat from his brow. âDonât forget, the Olympics are coming up and Uncle Sam needs shot-putters!â

Iola finally spoke up in defense of her brother. âNo fooling, boys, Chetâs really getting good at this.â

The stout boy threw out his expansive chest, balanced the shot in his right hand, and began to move his shoulders rhythmically.

âLet her fly!â Frank called.

Chet spun around and released the sphere.

âWow!â Joe cried out. The ball arced directly over the henhouse.

Crash! With the sound of splintering wood, mingled with the squawking of the fowl, the metal ball pierced the roof, leaving a jagged hole.

The noise brought Mrs. Morton to the back steps of the farmhouse. âChester!â she called out. âWhatâs all that racket?â

âOh, nothing to worry about, Mom,â Chet replied hastily. âSay, Mom, would you like to have chicken for supper?â But Mrs. Morton had already gone inside. Fortunately, as the young people discovered, Chetâs mighty missile had missed the chickens.

âChet, youâve got a great throw,â said Joe. âI mean it. What power!â

âYeah, but what a long time itâll take me to fix the henhouse roof!â Chet groaned.

The young peopleâs laughter was interrupted by Mrs. Mortonâs calling:

âFrank! Telephone!â

He rushed into the house, his face flushed with excitement. Joe ran after him.

âHello.... Jack? ... I thought it might be you.â

Joe stood by tensely. Then Frank burst out, âJust as I figured!â

CHAPTER VIII

New Strategy

JACK WAYNE had reported to Frank that someone using a high-powered rifle had fired a bullet into the propeller of the Hardy plane. It would take several days to get a new prop.

âThe gunman must have shot from a good distance,â Jack said. âHe probably hid in foliage outside the field.â

âOur enemy really wants to stop us,â said Frank.

âBut how did you know something like this might happen?â the pilot asked.

The young sleuth told him about their ruse and the events leading up to it. âJack,â he added, âthis shows we can turn that bug to our own advantage.â

âRight,â Wayne replied, âand perhaps lead the crooks into a trap. But next time tell me, eh?â

After Frank had apologized for the oversight, he relayed the entire conversation to Joe, Chet, and the girls.

âHa!â Joe was gleeful. âThey sure went for our bait.â

âNow itâs time to plan new tactics,â Frank said. âWeâll get the other fellows together for a meeting today.â

âAnd leave us out?â Callie gave a small pout.

âWe were going to invite you boys to a dance,â Iola said, dimpling.

Joe brightened. âA dance? When?â

âNext Wednesday. Itâs the annual Fresh Air Camp Benefit Ball,â said Callie. âWe were going to buy the tickets and surprise you.â

âThatâd be neat, but we canât make it then,â Frank said regretfully. âWeâll probably be far away from here.â

âLike Kentucky, maybe,â Joe put in. âCan we take a rain check?â

The girls were disappointed, but they wished the young detectives well and offered to help in any way they could.

âOkay,â replid Frank. âCan you suggest a good place for us to hold a secret meeting?â

âHow about Tony Pritoâs?â asked Callie. âThey have a terrific basement rec room. Remember the party we had there last spring?â

âPerfect,â Joe replied. He immediately telephoned the Prito residence. Tony was not at home, but his mother answered.

When Joe made his request, Mrs. Prito said, âBy all means, you boys come over. And save your appetitesâIâll make spaghetti and meatballs for all of you. You can hold your meeting after dinner. Weâll eat at seven oâclock.â

âThanks, Mrs. Prito, butââ

âNo trouble at all. Iâll tell Tony as soon as he gets home.â

âThatâs real nice of you, Mrs. Prito,â said Joe. âThank you.â

When Chet heard of the dinner plans, he was delighted. âGreat!â he declared. âSpaghetti and meatballs! Just what I need for building shot-putting muscles!â

Telephone calls were quickly made to Biff and Phil, who said they would come. Shortly before seven that evening, Frank and Joe drove to the Prito home, located on the north side of town. Chet Morton, who was the last to arrive, explained that he had practiced shot-putting until an hour before, just so he would be certain to have an appetite!

This statement tickled Phil Cohen. âChet, you could work up an appetite just twirling your thumbs!â

Tony explained that his father had gone to Kentucky the previous day. Mrs. Prito looked troubled. âMore bad luck on the road project,â she said, shaking her head. âI donât know when it will end. Of course, the worst of it is your fatherâs illness, Frank and Joelâ

For a while, however, the mood of worry was dispelled by the sumptuous spread that Mrs. Prito had prepared. The meal started with antipasto, followed by thick minestrone soup. By the time the boys had eaten their first helping of spaghetti and meatballs, most of their hunger had been satisfied. As usual, Chet was the exception.

Mrs. Prito watched with a broad smile as Chet accepted a second generous portion.

âBuilding up my strength,â he said, spearing a succulent meatball. After dessert of fresh fruit, the boys thanked their hostess.

âWow, that was some feast!â said Chet, patting his stomach. âIâll be a champion shot-putter yet!â

Biff grinned. âHow about a little exercise before we start the meeting?â Everyone agreed, and the boys clattered down to the basement.

In the spacious recreation room the Hardys, Phil, and Tony decided on a billiard game, while Biff and Chet trotted to the Ping-Pong table at the far end.

âThisâll get rid of that stuffed feeling, Biff,â assured the stout boy.

After a few minutes of warming up, the two engaged in a furious tilt. The sound of the bouncing balls mingled with the jolly banter of the billiard players.

As Frank lined up a shot to send the nine ball into the side pocket, a terrific crash filled the basement. This was followed by a loud âoof.â

Startled, the other boysâ companions wheeled around to face the Ping-Pong table. It lay flat on the floor, with hapless Chet sprawled out across it. Red-faced, as the others roared with laughter, he picked himself up.

âWhat happened?â Tony asked.

âI fooled him with a spin shot,â Biff said. âGood old Chet leaned over too far and that did it.â

Frank found that except for one splintered leg, no damage had been done to the table.

Joe and Tony quickly got tools from a workbench and repaired the table leg.

âOkay, fellows,â Frank said finally. âBefore Chet has any more accidents, letâs get down to business.â

First, Tony took the precaution of posting his German shepherd dog outside the basement door.

âAxel will warn us if anybody comes snooping around,â he said.

The boys seated themselves in a partitioned-off den-study, and Frank opened the discussion.

âJoe and I will lay our cards on the table. Weâve met with nothing but setbacks ever since we took over Dadâs case.

âYouâre not giving up?â Tony Prito put in quickly.

âOf course not!â Joe assured him. âThereâs no mystery that canât be solved, if itâs worked on long and hard enough.â

âRight,â Chet Morton said sagely. âYou two should know.â

Phil Cohen winked at Biff. âA hunch tells me you Hardys got us together to decide on a plan of action.â

Frank smiled. âYouâre right, Phil. You fellows have always stuck with us when the going got rough.â

Chet Morton nodded vigorously. âWhat else are pals for?â

âIâm glad to hear that,â Joe said, âbecause now we come to the heart of the matter.â

The Hardys were silent for a moment as Frank looked from face to face. âJoe and I,â he said, in measured words, âare asking each of you to join us on a dangerous mission.â

Chetâs eyebrows arched like the trajectory of a soaring shot. âDangerous? Where?â

âKentucky.â

The Hardysâ friends exchanged excited glances.

âYes,â Joe said, âletâs go to Kentucky and find out more about that sabotaged bridge and who dry-gulched Dad.â

The Hardys thoroughly briefed the others on their sleuthing so far, including the New York trip. They had just concluded when Tonyâs dog began barking.

âSomethingâs going on!â said Tony. He dashed to the basement door, opened it, and peered into the darkness.

The big German shepherd was leaping up at the shadowy figure of a man near the basement window!

CHAPTER IX

Fake Names

âDOWN, Axel!â A deep voice came from out of the darkness, followed by a happy whimper from, the German shepherd.

âItâs my father!â Tony exclaimed.

A sturdy-looking man, the dog bounding at his heels, stepped into the basement.

âHello, Mr. Prito.â Joe grinned. âFor a minute we thought you were a prowler.

The broad-shouldered contractorâs face, ruddy from years of outdoor work, creased in a smile,

âNot guilty. When I saw all those cars parked in the driveway, I thought maybe a political rally was in progress here.â

âFrank Hardy for mayor,â Phil quipped.

Everyone laughed, then sobered as Frank spoke up. âWe were having a powwow about your road job, Mr. Prito.â

The group adjourned to the den, where the contractor pulled up a chair and sat down wearily.

âIâm afraid we are licked.â

âDid something else go wrong, Dad?â Tony asked.

âMy men started to repair the bridge, and it collapsed again. This time we found an acetylene torch was used to cut through the stress points of the girders. The cuts were covered with a putty filler and painted over to resemble rivetsâso of course no one noticed anything wrong until the structure gave way.â

âWas anyone hurt?â Chet put in.

âFortunately, noâthey scrambled to safety in time.â Mr. Prito sighed. âUnless we can find out who is causing the sabotage, and prove it, I may have to give up the whole project.â

âAnd lose all that money?â Biff said.

Joe spoke up. âFrank and I were just asking the fellows if they could go to Kentucky with us. Our idea is to get jobs on the road crew and maybe then we can solve this mystery.â

âA bold idea. What is the rest of your plan?â

Frank first of all inquired if Mr. Prito had a trusted foreman who could handle the hiring of the boys.

âYes, John Losi. I sent him down to Kentucky temporarily, because the regular hiring agent, a local man named Bond Deemer, is on a weekâs leave from the job.â

âWhat could be sweeter!â said Joe.

Then the Hardys went on to explain their scheme. Each of the boys would get a different job. Tony could be a mechanic for road-building equipment, such as graders and earth-moving ma chines.

âBig Biff here could man a truck,â said Joe, and Frank suggested that Phil sign on as a timekeeper, to see whether anyone stayed away from work for any length of time.

Phil grinned happily. âGreat! Thatâll give me time to sketch.â

âHey, what about me?â demanded Chet.

âA laborer,â Frank said. âThatâll really build up your musclesâwhile youâre picking up gossip from the other workers.â

âSort of like a spy, eh?â

âThatâs right,â Tony interjected. âSecret agent 008, with the accent on the a-t-e.â

Chet grinned and accepted his new role. âAnd what may I ask, are Frank and Joe Hardy going to be? Spy supervisors?â

âEspionage foremen, so to speak,â quipped Tony.

âNot quite, pal.â Frank explained that the Hardys would work with the bridge crew. In that way, they could keep close tabs on the workmen in case one or more might be connected with sabotaging the project.

âBut everybody knows the name Hardy,â Mr. Prito said. âThe saboteurs would soon catch on that you are Fentonâs sons.â

In answer Frank pulled out a piece of paper from his pocket. âWeâve already worked that out, by each of us keeping his first name and changing only the surname.â

Joe added, âThe payroll records can be corrected for the government later, canât they, Mr. Prito?â

âYes, indeed.â

Frank unfolded the paper and spread it on the table.

âYou picked our fake names already?â Biff asked with a grin.

âSure thing, Listen:

Frank Teller
Joe Jensen
Chet Ball
Biff McGuire
Tony Gonzales
Phil Rubinow.â

âA masterpiece!â Phil declared. âJoe, youâre blond like a Scandinavian, and Tony could pass for Spanish.â

âBut what about Chet Ball?â asked Biff.

âOh, I get it,â said Chet. âThat metal ball Iâve been shot-putting.â

The boys began trying out their aliases on one another.

âBiff McGuire,â said Biff. âNot bad, sounds like a real rugged character.â

âAnd weâll need a few on this trip,â declared Joe.

By now the Hardys had generated such enthusiasm among their friends that Mr. Prito finally acceded to the plan.

âItâs a risky one, remember!â the contractor warned. âBut good luck. You can reach me here if necessary. I have several other projects going.â

Frank and Joe suggested that the other boys leave Bayport one by one, at varying times, in order to avoid attracting attention.

âWeâre leaving on the early bus tomorrow morning,â said Frank. âWeâll see you all in Kentucky.â

On the way home Joe was jubilant. Now that they had hoodwinked their enemies by their own microphone, he was sure the criminals could be thrown completely off the trail.

Joe laughed. âMaybe we can say weâre going fishing in Canada, or something like that.â

âI hope we can fool them, but letâs not count our chickens too soon,â Frank said as they drove into the garage.

So exuberant were the two boys that they dashed through the kitchen and raced upstairs to their fatherâs study. Frank closed the door, winked at his brother, and mustered up his most doleful voice.

âJoe,â he said, âthis case is too much for us. I think we should quit and let the police handle everything.â

With a mocking expression, Joe jabbed his finger over the back of his shoulder toward the bug on the ceiling. âRight, Frank. We know when weâre licked.â

Just then there was a quiet knock at the door. When Joe opened it, Mrs. Hardy beckoned them into the hall and down the stairs. In the living room she whispered, âYou two came in so fast, I couldnât tell you.â

âTell us what?â queried Frank, noting his motherâs look of alarm.

âCome, Iâll show you.

Aunt Gertrude joined them. She, too, seemed fearful.

âOh, do be careful, Frank and Joe,â Miss Hardy said in a strained voice.

Joe scratched his head. âWhatâs this all about?â

Mrs. Hardy walked into the kitchen, picked up a flashlight from the table, and led her sons into the side yard. She played the beam up the house. Her sons gasped. A light nylon rope, looped around the chimney top, ran past an attic window to within a foot of the ground.

âGertrude and I noticed it when we came home from the hospital,â Mrs. Hardy explained.

âGreat gophers!â Joe exclaimed. âSomebody climbed up there!â In a moment the boys were bounding through the kitchen, into the hall, up the stairs and into the attic. Frank turned on the switch and the attic was flooded with light. The Hardys took one look and groaned. The radio transmitter was gone!

The trickers had been tricked!

Joe hastened to the window near the chimney and looked out. The nylon rope dangled only inches away from the sill.

âThe monkey man!â Frank exclaimed.

The boys looked at each other, sick with fury over the way they had been outmaneuvered. Suddenly there was a crash, followed by a tinkling of glass.

âItâs downstairs,â Frank said. âCome on!â

The boys ran to the first floor. They arrived in the living room to find Aunt Gertrude and Mrs. Hardy standing motionless, their faces registering shock.

âWhat happened? Whatââ

Joe pointed to the living-room window, which had a large, jagged hole in the center. The boysâ gaze traveled to the rug, on which lay a large ball bearing with a paper wrapped loosely around it.

Aunt Gertrude found her voice. âThieves! Criminals! Murderers!â she cried shrilly.

Frank snatched up the paper, and with hearts pounding, he and Joe read the message: âWise guys stay in Bayport.â It was signed with the three-looped letter M.

CHAPTER X

Monkey on a String

THE latest threat from the Hardysâ enemies only served to stiffen the boysâ resolve. Frank and Joe quietly left the house and stealthily searched the grounds. But they discovered no clue to the missile hurler.

Frank stopped at the dangling nylon rope and yanked it hard. It was firmly fastened around the chimney.

âThe fellow must be great with a lariat,â said Joe. âWonder why he left it here.â

Frank had a theory. If the intruder had been surprised by Mrs. Hardy and Aunt Gertrude, he might have shinned down a drainpipe on the other side of the house.

âWithout time to unfasten and take his rope,â Joe added.

âRight.â

The boys had a whispered conference.

âOkay!â Joe said. âLetâs try it!â

They confided their reasons for the Kentucky trip to their mother and Aunt Gertrude. The women, although apprehensive, did not oppose the idea.

âWe found your father better this evening,â said Mrs. Hardy. âBut heâs still not fully conscious. I suppose he would want you to take his place.â

Next, Joe phoned Radley, telling him of their plans. Sam approved heartily and wished the boys success.

âIâll keep an eye on your dad and your house,â he promised. âKeep me posted.â

The boys then got out their suitcases, and as they packed, cut off all telltale labels from their clothing.

âHave you got the binoculars?â asked Frank.

âRoger. And our miniature radio transmitter.â They were about to shut their bags when Mrs. Hardy and Aunt Gertrude came into the room.

âDo you have your heavy sweaters?â Miss Hardy asked with an air of authority. âKentucky isnât Miami, you know.â

âBut, Aunty, weâre not going to the North Pole!â Joe protested. âBesides, itâs summer.â

âNever mind. It still gets chilly in the woods at night,â she insisted.

âAll right,â Frank agreed. He reached in the closet and pulled out two heavy wool sweaters which he and Joe hurriedly packed.

âAnd now, Mother,â Frank said, âwill you drive us to the bus depot? We can catch the midnight bus.â

After receiving parting admonitions and a hug from their aunt, the boys and Mrs. Hardy got into the car and soon were at the terminal.

âThis bus to Kentucky goes via Pittsburgh, Mom,â Frank said. âGood-by and donât worry.â

He and Joe embraced their mother, then swung aboard. A few minutes later, with a roar of its diesel motor, the vehicle swung out onto the main street. But it had gone only four blocks when Frank tapped the driver on the shoulder.

âWeâd like to get off here, please.â

âWhat? Weâve hardly started,â argued the driver. âThis isnât a local, yâknow.â

âItâs very important,â Joe said solemnly.

âOkay, okay.â

The bus stopped at the next corner and the boys hopped off. They strode rapidly back home, approaching the house cautiously from the rear. Nimbly they hopped a fence into their backyard. Silent as shadows, the Hardys cached their suitcases behind the garage, then crept to a sheltering clump of rhododendrons. Tensely they waited, their eyes fixed on the chimney.

Joe whispered, âDo you really think someone will come back for the rope?â

âSure.â

Earlier Frank had reasoned that their enemy was watching for his opportunity to return to the Hardy home undetected and retrieve the rope. Therefore, he would be more likely to do so if he thought the brothers had left town.

Half an hour passed. Forty-five minutes. Joe glanced into the starry sky and saw that Orion had moved some distance west in the velvety black sky. The boysâ muscles ached.

âFrank, I donât think anybody willââ

Joeâs words were cut off by a nudge from his brother. The crouching boys peered through the shrub at a small figure creeping around the side of their house. Joe put his mouth to Frankâs ear. âThe monkey man!â

âSh!â

The prowler stopped, listened, then advanced toward the nylon rope. The Hardys were tense with excitement, but dared not move a muscle lest they scare off their enemy. They must capture him at any cost, if their trip to Kentucky were to bring results. Otherwise, the monkey man would be certain to give away the Hardysâ identity, and alert those mixed up in the bridge sabotage.

The intruder waited as if to make sure everyone was safely asleep in the darkened house. Then the man sprang to his full height, which was a scant five feet. Like a cat, he glided up to the rope, seized it, and began virtually walking up the side of the Hardy house.

The boys put their plan into action. Cautiously Joe moved from his hiding place, quietly unlocked the back door, and sped upstairs in the darkness. Frank, meanwhile, darted to the dangling rope and began to pull himself up hand over hand.

The jerk on the rope signaled Frankâs presence. The monkey man, now halfway to the roof, uttered a high-pitched cry. The lights in the house blazed on, and Joe stepped out of the attic window close to the rope. He, too, seized the nylon rope and began to slide down it.

The monkey man was caught between the Hardys!

He shrieked in rage and defiance. âYou wonât get me!â

With that, he crashed through the screen of an open second-floor window. Instantly Frank dropped to the ground. A moment later he heard a scream, a bang, and a thump coming from downstairs. He dashed inside to find the monkey man picking himself up from the hall floor at the bottom of the stairs. Aunt Gertrude stood nearby, brandishing an umbrella.

âCrashed right into me!â she gasped.

Frank made a dive for the intruder. Then Joe, halfway between the first and second floors, leaped from the stairway and landed on the monkey manâs back. As the trio rolled over and over, the trapped prowler, though small, fought with the fury of a wild animal. His arms and legs writhed like snakes as he tried to escape the Hardysâ steel grip.

Disheveled and bruised, the boys finally subdued the monkey man, and sat astride him. Mrs. Hardy had called the police and soon a squad car roared up. A lieutenant entered and snapped handcuffs on the prisoner.

Chief Collig arrived minutes later, having received word of the fracas at his home.

âDo you know this man, Chief?â asked Frank as the monkey man glowered at his captors.

âIâll say. Heâs on the wanted list. His name is Monk Smith, an ex-con.â

Frank and Joe told Collig of Smithâs trash-can assault on them in New York. âWe figure,â Joe added in a low voice, âhe fits in somewhere with the bridge mystery Dad was working on.â

The chief turned to the prisoner. âWho put you up to this caper, Monk?â

Smith only scowled, and would not reply to this question or to any others.

âOkay, take him down to the lockup,â Collig instructed finally. âMaybe heâll sing there.â

The police chief said that the ex-con would be held without bail for a few days, in order to give the Hardys a better chance to work incognito in Kentucky.

After the police car had sped off, the boys took down the rope. âThis might come in handy,â Joe said as he coiled the light nylon and put it in his suitcase.

The monkey man was caught between the Hardys!

In a short time the brothers said good-by again to their mother and Aunt Gertrude.

Joe grinned. âThis time weâre really Kentucky-bound.â

He and Frank took a taxi to the bus terminal, and caught the next trip out. Settling back in the comfortable seats, the weary young sleuths soon fell fast asleep as the bus hummed along the dark highway.

The next day found the Hardysâ pals leaving Bayport as arranged, separately and at different times: first, Tony; next, Chet; third, Biff; and Phil was last to depart. Their arrival times were spaced so that over the weekend, each made his way independently to the construction shack of John Losi.

Mr. Pritoâs trusted assistant was expecting them, and without delay assigned the four to their respective jobs. Monday, their first day at work, was a busy one. It was not until Tuesday morning that the Bayporters became worried about the delayed arrival of the Hardy boys. Chet rested on his shovel next to a pile of dirt alongside a section of freshly poured concrete.

âWhere are Frank and Joe?â he wondered. âThey left before any of us did.â

Among the swarms of workers in the densely wooded area Chet could make out his three cohorts. Tony, stripped to the waist in the hot sun, was repairing a tractor by the roadside. Biff was driving a concrete mixer, while Phil Cohen, busy writing on a clipboard, stood near an abutment of the bridge under construction.

A brusque voice at his elbow startled Chet.

âWeâll never build this road with you leaning on your shovel, buster.â

The newcomer, a sandy-haired, hard-eyed man, told Chet he was Bond Deemer, the regular hiring agent. âI just got back this morning before Losi left. When did you come on the job?â

Somewhat taken off guard, Chet stammered, âWell, ah, weâIâgot here late Saturday, when Mr. Losi hired me.â

âWhatâs your name?â

Chet gulped. âChet Ball.â

âOkay,â said Deemer. âI expect a full dayâs work. Understand?â

Deemer strode off and Chet resumed shoveling. The hefty boy glanced up now and then at his strange surroundings. Across from the road site, set among the pine trees, were five trailers. Four were used as bunkhouses and the fifth, much larger, contained the kitchen and commissary.

Despite his gloomy mood, Chet felt hunger pangs. âWish it was chow time,â he thought. The nearest town, Boonton, was too far away for a quick hop to obtain a sack of hamburgers.

Chetâs eyes roved to the wide, gushing stream and the bridge, built halfway across. This was the one, he knew, that twice had collapsed, and now the crew was busy pushing its construction for the third time.

Almost unconsciously, Chet again paused in his work. How could they do any sleuthing without Frank and Joe? he asked himself disconsolately.

âHey, Ball!â A lantern-jawed man hopped off the cement mixer and strolled toward Chet.

âWh-who, me?â

âYour name is Ball, isnât it?â

âYes, Mr. Angan,â Chet replied hastily.

It hadnât taken the newcomers long to learn that Robert Angan was the foreman, and a rough task-master at that!

âLook, Ball, youâre not paid to stand there like the Statue of Liberty! Get to work!â

Embarrassed, Chet dug his shovel deep into the loose dirt. âThatâs right,â Angan needled. âAct like youâre alive!â

A few minutes later Chet straightened up to ease his aching back. Across from him he spied two sturdy youths in dungarees hauling a large log on their shoulders. Chet bravely restrained a whoop of joy. Frank and Joe Hardy!

Frank, in the lead, gave a slight nod of recognition as he and Joe proceeded toward the bridge. Chet started to whistle, and dirt flew furiously from his shovel.

âHey, Ball, thatâs more like it!â yelled Angan.

A shrill blast from a steam whistle signaled the noon hour. Trucks and construction vehicles ground to a halt, and all the workmen headed toward the commissary. Meals were eaten on long, rough-hewn tables inside the trailer. Many of the old-timers sat together, talking and joking as they ate.

Frank, Joe, and their friends managed to find seats near one another, but chattered casually as if they had just met. Across from the Hardys sat a tall hillbilly youth. He had large hands and a long neck, and his Adamâs apple bobbed up and down when he swallowed.

âMy name is JensenâJoe Jensen,â Joe Hardy said, extending a hand.

The youth looked up shyly from under a shock of brown hair. âMineâs Willy Teeple.â

âLive around here?â asked Joe.

âYup.â

The Hardys could see that Willy was not one for conversation. The sentences he spoke were barely longer than one or two words. The foreman, Angan, who happened to be at the boysâ table, seemed to take great delight in riding the work men.

âSee here, Gonzales,â he said to Tony. âIf you donât get that tractor fixed pretty soon, youâll be heading back south of the border!â

âYes, sir!â Tony replied.

âDonât sir me!â Angan shot back. âJust do what youâre hired for.â

âYes, Mr. Angan.â

âAs for you, Jensen, you dumb SwedeââAngan turned to JoeââI noticed you bothering the guys with questions. What are you? A reporter?â

With difficulty Joe held back a retort and mumbled, âSorry.â

Chet, ravenous, reached for a third piece of bread. He changed his mind abruptly as Angan stared at him.

âWe donât like heavyweights on our crew!â the foreman said pointedly.

Having finished, Chet rose to leave. As he neared the end of the bench where Angan sat, Chet accidentally jostled the manâs elbow, and the cup of coffee he held spilled over the table.

âDummy!â roared Angan, jumping up. With one hand he grasped the front of Chetâs work shirt and twisted it until the buttons nearly popped. His other fist cocked back. âFor two cents Iâdââ

Without warning, Willy Teepleâs big hands grasped the foremanâs wrist in a viselike grip.

âI wouldnât do that, Mr. Angan,â Willy said softly.

CHAPTER XI

Jailbird Language

WILLY TEEPLEâS grasp prevented Anganâs fist from sailing to its mark on Chetâs jaw. The foreman released him and swung on Willy. At the same instant, Bond Deemer ran over and forced himself between the two.

âWhatâs the idea of interfering, Teeple?â Deemer thundered. âAngan handles the men around here.â

The hillbilly backed off, his face showing no resentment. âOkay, Mr. Deemer,â he said.

Chet, meanwhile, had stood by half stunned by the foremanâs sudden violence. His pals had found it hard not to go to his aid. To their surprise, Angan turned to Chet apologetically.

âIâm sorry, Ball,â he said. âI shouldnât have lost my temper. But weâre in an awful mess around here and my nerves are on the raw edge.â

âThatâs all right, Mr. Angan,â replied Chet, relieved.

âYou know whatâll happen if our bad luck continues,â Angan said, looking about in appeal to the onlooking workmen. âThe Prito company will be penalized five hundred dollars a day for every day extra it takes to finish this job beyond the time weâve contracted for.â

Tony spoke up. âI guess that would just about put Mr. Prito out of business, wouldnât it?â

âIâm afraid so,â Angan replied, âand Pritoâs a good guy.â

âOkay, break it up,â Deemer ordered impatiently. âBack to work.â

With a scuffle of heavy boots, the workmen filed out of the commissary. On the way Chet thanked Willy for coming to his rescue. The gangling youth gave a quick nod and turned off. Soon power shovels were chugging and earth-moving equipment went bouncing over the rough, unfinished portions of the highway. Working together, Frank and Joe found an opportunity to discuss the work gang.

âItâs hard to tell whoâs friend or foe,â Joe remarked. âBut I guess itâs too soon to form any suspicions.â

The Hardys agreed that Angan, although hot-tempered, seemed to be regular.

âHe was actually sorry for Mr. Prito,â Frank observed.

âDeemerâs not especially good-natured, either,â said Joe. âBut he seems okay.â

The Hardysâ contact with their pals for the rest of the day was brief and surreptitious.

âAnything new?â Frank asked as he passed close to Chet.

âNo.â

The same question, whispered in passing, to Phil, Biff, and Tony also produced a negative reply.

After the evening meal was finished, Frank drew his brother aside. âWeâve got to do some sleuthing tonight,â he said.

The Hardys sauntered amid the workmen lounging about, some smoking, others chatting in front of the bunk trailers. Frank sat on a tree stump while Joe flopped on a grassy knoll nearby. Soon they were casually approached by Tony.

âHi, there,â he said in a loud voice. âHow do you like working here?â Then, in lowered tones, he added, âWhat took you both so long?â

In a nonchalant manner, but with a guarded voice, Frank explained that he and Joe had stopped to investigate the town of Boonton.

âWe thought weâd give the rest of you fellows a chance to get settled on the job before we showed up,â Joe put in, adding that they had checked in with Mr. Losi just before he had left for Bayport earlier that morning. The brothers had learned that no one named Felix was on the work force.

Frank told of the equipment they had brought. âWeâve got the binoculars, a nylon rope, and a miniature short-wave radio set hidden in a large cinder block under our bunk trailer.â

âGood,â Tony said with a smile. âThe rest of us only brought muscles. And do we need âem!â

As it grew dark, cool air settled down from the hills and the tired workers drifted away to turn in for the night.

Frank and Joe were billeted in a trailer away from the rest of their pals, with Frankâs bunk located above Joeâs. Near midnight the Hardys, careful not to awaken their bunk mates, sneaked outside and noiselessly made their way to the neighboring trailer, housing Angan and Deemer. Voices came from inside.

Joe stood on his brotherâs shoulders and peered through one of the windows. Angan was sleeping. Deemer was sitting cross-legged on the floor, playing cards with two men. Willy Teeple looked on sleepily.

As one of the workmen turned his head, Joe ducked out of sight and dropped to the ground. The Hardys pressed close to the metal wall of the trailer and listened intently. The language of the card players was interspersed with many slang words which the boys had never heard before. It certainly was not the jargon of their Bayport High School crowd! The young sleuths made mental notes of the odd expressions.

Pair of bins; oiler; half stamp; clobby joint; long nit; bath in the canal; bice; baron.

âWhat kind of lingo is that?â Joe whispered.

Suddenly there was shuffling of feet and Deemer said in a loud voice, âWilly, you be the long nit tomorrow.â

âTheyâre breaking up!â Joe muttered. He and Frank hastened to their own bunks and quietly climbed in.

Next morning, as the Hardys dressed, Frank whispered to his brother, âJoe, I think I have it solved. I remember Dad speaking about convict lingo, and some of those words last night sounded like jailbird slang.â

âGood night!â Joe exclaimed. âWe may be in a hornetâs nest of ex-cons.â

The workday started early and the Hardys were assigned by Angan to carry planks for the carpenters who were building concrete forms to be used for the bridgeâs support columns. They spotted their four buddies as they passed by. Frank and Joe also noted that Willy Teeple was nowhere to be seen.

At midmorning the workmen paused for their coffee break. This gave Frank the chance he had been waiting for. He hastened to his bunk trailer, crawled beneath it, and removed the small radio. Concealing it under his shirt, Frank hurried back to Joe and slipped him the set.

âQuick!â Frank whispered. âNobody is working on the bridge now. Thereâs a good hiding place underneath the abutment. Contact Radley and ask him about those strange words.â

While Frank stood guard some distance away, Joe nonchalantly ambled over to the bridge. He made sure no one was looking, then ducked underneath, turned on the transmitter, and called Radley in Bayport.

After a few tense minutes of waiting, Joe got through to his fatherâs operative. He spoke rapidly, asking about the odd vocabulary the boys had heard the night before.

âThatâs con language, all right,â Radley said. âJoe, be extra careful!â

Radley translated the words which Joe carefully memorized:

Joe thanked Radley and signed off. Then he thought in surprise âSo thatâs why Willyâs not on the job todayâheâs lookout for that con bunch.â

Joe secreted the short-wave radio in his clothes and started to climb out from under the bridge. Suddenly he stopped short. Nearly concealed behind an empty cement bag were three sticks of dynamite! Joe examined them gingerly. They were not as yet connected with any detonating device.

âSo thatâs next on the gangâs listâblow up the bridge!â Joe thought, picking up the sticks. Just then he heard the familiar birdcall whistle used by the Hardy boys to warn each other.

Before Joe had a chance to move, Robert Angan scrambled down the slope. He glared angrily at Joe. âSo youâre one of the guys making trouble for us!â Angan said, and snatched the dynamite sticks. âWhereâd you get these?â

Joe pleaded innocence, explaining that he had gone under the bridge to cool off during the break and had spotted the explosives there.

âThatâs a great story,â the foreman snorted. He hid the dynamite sticks in his shirt so that the others would not notice them. Then he marched Joe directly to the project shack. Bond Deemer was working on some papers.

Angan produced the explosives. âCaught Jensen here with it.â

Deemer was speechless for a moment, then he stormed, âYou sneak. Youâll go to jail for this.â

âBut I had nothing to do with this dynamite!â Joe protested. âRemember, I just started work yesterday. Somebody else put these sticks under the bridge.â

âListen, Jensen,â Angan said, âI had you pegged for a troublemaker the minute you showed up here.â

Deemerâs anger had receded. He tapped his pencil and looked thoughtfully at Joe. âWe canât afford to lose men on this job. Angan, I believe the kidâs telling the truth about the explosives.â

âOkay,â said Angan, pacing nervously. âItâs your responsibility, Deemer. But one false moveâ âhe pointed at Joeââand youâre through!â

This time Angan assigned Joe to learn to run a grader machine. âSo I can keep you in sight,â he said.

Later, the foreman approached Frank. âYou there, Teller!â he called. âI want you to learn how to handle a pan.â He pointed to a huge high-wheeled earth-carrying machine stopped beside the road and Angan called up to the driver, âYancy, teach this kid how to operate it, then he can spell you.â

Frank climbed on to the monster machine, the rubber tires of which were taller than he. He found Yancy to be a bluff individual, sun-tanned, with bulging arm muscles and a broad face.

The machine started to bounce along, and Yancy readily explained its mechanics to Frank. After the machine had dropped a load of dirt by the side of the road, Yancy turned to his new assistant. âYou got an easy job, kid. You must know the baron.â

âWho?â Frank could have bitten off his tongue. From that moment on, Yancy said not a word and it was all work and no talk.

Several times Frank tried to start a friendly conversation, but with no luck.

At the end of the dayâs work, the Hardys met beside the swift-moving stream to wash up.

Frank told his brother of Yancyâs clamming up after he had asked who the baron was.

âDo you know where Yancyâs bunk is, Joe?â

âYes, in Deemerâs trailer.â

âThen I think Iâll do a little eavesdropping tonight,â Frank said.

An offhand exchange with the other four boys proved that they had uncovered nothing unusual during the day. Late that night Frank sidled up to Yancyâs trailer and put his ear close to the door. The voices inside were subdued, but clear enough for the young sleuth to identify as Yancyâs and Deemerâs. The boy held his breath and listened intently, noting certain words he was sure were underworld lingo.

Frank heard Deemer mention Joeâs name in connection with the discovery of the dynamite. Then Yancy spoke up. âWhat about this Frank Teller? I thought he was an apple, but he ainât.â

A third voice said, âI hear by the grapevine Teller did a bice.â

A cold chill went up Frankâs spine. So they thought he was an ex-jailbird! âNo wonder Yancy figured I knew the baron!â Frank gritted his teeth. âIf only I hadnât asked âwhoâ?â

Suddenly there was a noise nearby. Frank ducked around the trailer and flattened himself against it as a flashlightâs beam stabbed the darkness.

CHAPTER XII

The Protector

FRANK held his breath as the light flashed about near the entrance to the trailer. Then it went off. The door squeaked open and shut.

A voice from inside said, âOh, itâs you, Willy. What a layabout! Here, give me the glasses.â

âArkitnay!â retorted Willy Teeple. Frank heard two heavy boots drop to the floor, then all grew silent. Frank waited, but no further talk came from within, so he quietly returned to his own trailer. Inside he whispered to Joe:

âFirst we have to prove those ex-cons are doing something crooked here. In that case, maybe the police can help us. But weâre up against a tough assignment, Joe. Come on. Letâs contact Radley again.â

The two boys took flashlights and slipped out of the trailer. Joe retrieved the radio set, then the Hardys cautiously made their way into the woods bordering the road.

Once out of sight of the work camp, Frank flicked his light on and off just enough to pick their way through the dense forest. Progress was slow.

âDo you think itâs safe to stop now?â asked Joe.

âNo. They may have a lookout this close to the trailers.â

Stumbling and groping, Frank and Joe plodded on through a stand of pine trees. Finally they came to a small clearing, where the moonlight illuminated a huge boulder. The Hardys dropped to the ground, their backs against the stone.

âOkay,â said Frank. âLetâs get Radley.â

Joe turned on the transmitter, then put in the call to Bayport. No response.

Joe tried again, without results. âDid you check the batteries?â asked Frank.

âThereâs plenty of juice,â his brother replied.

Just then a ham operator came in strong and clear. He asked Joe where he was located.

Joe was polite, but said this was an emergency call and would the ham please sign off.

âAs you say. Good luck. Over and out.â

âWhew! I hope the cons arenât listening in,â said Frank.

âIf they are, weâre sunk!â declared Joe. He called Radley again. This time a faint reply reached their ears among interference. Joe tuned out some of the static.

âSam? ... This is Joe. Howâs Dad?â

The reply was heartening. Fenton Hardy was improving steadily! âHe has intervals of lucidity,â Radley reported, âbut his memory is foggy.â

The operative went on to say that X rays had shown the reason for this. âFenton must have been hit in the back of the neck,â Radley said. âThe doctors feel that his memory wonât be clear for at least a week or so.â

âBut he will get better!â Joe said tersely.

âDefinitely.â

With a sigh of relief, Joe passed the radio to Frank, who told Sam, âIâve heard more of those jailbird words. For instance, they called me an apple. Whatâs that?â

âA swindler.â Radley chuckled. âThey think youâre a crook, Frank. Thatâs good!â

âDonât tell Aunt Gertrude!â Frank grinned.

âGot a pencil and paper?â Radley asked. âI can give you a list of prison slang your father compiled.â

âRoger.â

Joe turned on his flashlight and laid it on the ground. Then, as Sam dictated, he jotted down:

Suddenly Radley was cut off.

âOhâoh, whatâs up?â Joe fretted.

âBad atmospheric conditions, probably,â Frank said. âWeâd better get back.â

âOkay, swindler,â needled Joe. âWe have enough words to work on.â

They started back as quietly as they could. But it was impossible to avoid stepping on twigs which snapped and cracked loudly. Frank used the light sparingly, as a precaution against being spotted.

Suddenly Joe said, âHey, look!â

Just ahead of them lay a narrow path, which came to a fork. A right turn would lead them to the camp. The left-hand trail headed in the direction of a mountain ridge. Frank bent down and flashed his light over the ground near the path. Among the matted pine needles was a half-burned safety match.

âSomebodyâs been using this trail, and more than likely one of the workmen,â Frank commented.

âLetâs follow it toward the mountain,â said Joe.

âSort of late now.â

Joe was not to be dissuaded. âBut we might find a good clue.â

âOkay, but we canât be long,â Frank replied.

At first the path was easy to follow, with the moon providing enough light to guide them. But as the Hardys reached higher ground, a series of switchbacks made the going laborious.

Joe stopped suddenly. âSay, Frank,â he whispered, âdo you suppose this leads to some kind of lookout spot?â

Instead of answering, Frank seized Joe by the wrist and pulled him behind a pine tree. âI thought I saw something move!â He pointed to an opening between the pines.

âI donât see anything,â said Joe.

âFollow me!â Frank ordered. Getting down on all fours, the boys crept across the trail, flattening themselves now and then to listen. They heard a clink, like the sound of metal.

Frank skirted around the trees, then stopped at the edge of the opening. Here the pines grew so close together they completely obscured the moonlight.

Joe inched up beside his brother. âIt looks like a cave of some kind,â he whispered.

Frank nodded, pointing to a stump some thirty feet away, atop which was a boxlike object.

The boys lay side by side in the darkness, wondering what to do next. Was someone hiding in the cave? Should they risk entering it? Or should they wait and come back later?

âWe have the advantage of surprise,â Frank said finally. The boys rose to their feet, then tiptoed forward. Now they could see plainly that the opening was indeed a cave.

âWhen I shine the light, weâll dash in,â Frank said. Click. The flashlightâs glare revealed two eyes gleaming at them, as a menacing growl issued from the cave mouth.

âGood night!â Joe cried out. âA bear!â

As the huge beast lunged from the cave, the Hardys turned and fled. The growls of the bear became fiercer as it crashed through the trees.

Frank and Joe fairly flew onto the trail. Suddenly the bear gave a loud grunt. This was followed by a ferocious thrashing about. Soon the boys realized that the animal was no longer pursuing them. They halted, trembling and out of breath.

âWhew! I thought we were done for,â Frank said. âA black bear that size can tear your head off.â

The young detectives retraced their steps cautiously to the spot where the bear had stopped. âThere he is.â Joe pointed, and Frank shone his light on the animal. The boysâ jaws dropped in astonishment. The bear was fettered by a long chain, at which he strained toward the box on the stump, two feet away.

âLeapinâ lizards!â Frank exclaimed. âThatâs a beehive!â

âWhat a fiendish setup,â said Joe.

The Hardys deduced that someone wanted the trail guarded and had done this by keeping the bear chained in the cave, tantalizing it day and night by a feast of honey just out of reach.

The length of the chain was cunningly contrived, the boys observed. It extended across the trail so that an unsuspecting wayfarer would be frightened out of his wits, or even gravely injured by the voracious bear.

âBears normally stay out of peoplesâ way,â Frank remarked, âbut this one has a right to hold a grudge against humans.â

Making sure to stay clear of the bearâs flicking claws, the boys lifted the hive from the stump and heaved it close to the bear, whereupon the animal quickly ripped the hive apart and began to devour the honey.

âWow! Somebody is going to be surprised!â Joe said with a chuckle.

They speculated on the reason for the âbear trap,â and who was responsible, and wondered if it had any connection with their case. The boys started back along the sloping trail. As they descended, the Hardys were startled to hear a manâs voice calling:

âHey, Swede! Teller! Are you there?â

âItâs Deemer,â Frank whispered. âLetâs lie low. We donât want to tip our hand yet.â

The Hardys dived behind a thicket and crouched motionless, hardly daring to breathe. Suddenly came the sharp crack of gunfire! Bullets whizzed overhead, thudding ominously into the trees. Then it was quiet. Finally the cracking of twigs came to their ears.

As the sound gradually grew fainter, Joe took a deep breath. âHeâs leaving. Why do you suppose he shot at us, Frank?â

âHeâs jittery.â

The Hardys made their way cautiously along the trail behind the rifleman. But, again, they were halted by a strange happening. Through the trees a weird rosy pink glow spread over the sky.

âGood grief!â said Joe. âItâs not sunrise yet!â

The eerie light gave the black sky an awesome tint.

âThis is the spookiest spot Iâve ever been in,â Joe murmured.

âAnd the most dangerous!â Frank added.

âIâll say! Maybe thereâs a forest fire!â But Joeâs guess proved wrong when the pink light soon vanished and all was dark again.

Mystified, the Hardys went on toward the work camp. Every few feet they stopped to listen. The thought of Deemer, perhaps lying in wait to ambush them, caused the boys to break out in a cold sweat. Finally the trailers came into view.

âLook!â said Frank, halting abruptly. In the moonlight they could see Deemer sitting beside the door of their trailer, holding a rifle between his legs.

âOh, swell!â Joe said in disgust. âHow do we get in?â

The boys decided on a decoy action. Joe scooped up a rock and hurled it full force over the trailer. It landed with a thud. Deemer leaped up. Joe tossed another large stone in the same direction.

This time the hiring agent darted out of sight around the trailer.

âInside, fast!â hissed Frank.

He and Joe sprinted from the trees and slipped into their sleeping quarters.

They undressed silently in record time and climbed into bed. When Frank adjusted his pillow, his hand touched a piece of paper. âAnother warning,â he thought. By using his flashlight under the cover, Frank read the note. It was from Biff and read:

âPhilâs in trouble. Going to be fired. Caught making sketches of D and A.â

CHAPTER XIII

Surprise Password

FRANK whispered the message to Joe just before the screen door opened. Deemer stood silhouetted in the doorway, a gun in his hand. He tiptoed over to look at Frank and Joe, who feigned sleep. Joe sat up, as if alarmed.

âSomething wrong, Mr. Deemer?â

âW-why, Iâerââ The hiring boss was clearly flustered. âI thoughtâerâyouâd both gone into the woods and gotten lost. Itâs dangerous there, especially at night.â

Frank, too, sat up and put on a sleepy act. âMr. Deemer, do you usually carry that equalizer?â Joe asked.

Frank turned on his brother and snapped, âArkitnay!â

Deemer almost dropped the gun and his eyes bugged. He opened his mouth to speak, then evidently thought better of it. Without a word he stalked off to his own trailer.

âWe got him worried, anyhow,â Joe said with satisfaction.

âYes, but weâll have to be careful. Weâre still in the dark as to what his game is.â

Despite only a few hoursâ sleep, Frank and Joe awoke refreshed and keyed up for the sleuthing which lay ahead. At breakfast Frank casually seated himself next to Phil and said, âWe heard what happened.â Amid the clatter of utensils, Frank instructed his friend, âIf youâre fired, put on a sad face. Soon as you can, go to Boonton and stay at the Eagle Hotel. Weâll get in touch with you there.â

Phil nodded. Further conversation was impossible because Bond Deemer arose and pounded on the table for attention. âQuiet! Quiet!â

A hush fell over the workmen. Deemer turned to stare at Phil and a sarcastic smile curled his lips. âRubinow,â he said, âif you want to draw pictures, okay. But not here. Youâre fired!â

With a stricken look, Phil asked, âWhen?â

âRight now.â Deemer pulled a brown envelope from his pocket and flung it at the boy. âHereâs your pay. Scram!â

Amid the murmur that arose, Phil, pretending to be stunned, took the envelope and left the trailer.

âHeâs a layabout, anyway!â Frank said in a voice that could be plainly heard. A few eyebrows were raised among the men, but there was no comment.

Later, at the busy construction site, Frank climbed aboard the pan next to Yancy. The motor thundered and growled as the big machine responded to Yancyâs touch. It scooped up a huge bucketful of dirt, then trundled off to deposit it by the side of the highway. As they started back for another load, Frank decided to put out a few feelers.

âYou think Iâm a bindlestiff, eh, Yancy? I figured you to be a finger.â Yancy, surprised, jammed on the brake so hard they both nearly flew off the seat. Frank continued, âIâm a torch man, but a tin star caught me on a cheeser. Ainât it the way? Copped a heel but fell flat.â

Yancy gave the machine more gas. âYouâre okay, kid, but stow the con gab. The baron donât like it. We ainât all in the club.â

âWhat about the local yokels?â Frank parried.

âMost of âem are okay. Theyâre all scared of Rosy.â

âRosy?â Frank thought fast. âThe big fire at night?â

Yancy turned, grinning. For a fraction of a second he did not look where he was going. The machine hit a rock projecting from the roadbed and tilted crazily.

âJump!â Yancy yelled and dived from his seat. Frank followed suit, landing unhurt on the soft shoulder of the road. The vehicle flipped over with engine racing and wheels twirling madly.

Frank and Yancy dived from their seats

Frank and other workers ran up to Yancy, who had landed on a hard-packed surface. He lay moaning, clutching at his right leg. Angan hurried over, looking disgusted. âYouâre supposed to be an expert!â he growled. âWhatâs the matter with you?â

One of the men arrived with a first-aid kit. He stripped the coverall from Yancyâs leg, and after examining the injury, said, âAfraid itâs a bad fracture. Weâve got to get him to a hospital.â

A temporary splint was applied to Yancyâs leg. Grimacing with pain, he was placed on a stretcher, which two men slid into the back of a small truck. It eased onto the completed section of the highway and sped away.

Angan turned his attention to Frank. âWhat happened, Teller?â

Frank shrugged. âCouldnât say.â

The foreman scowled. âYou guys stick together pretty thick!â he said. âPick a partner, Teller, and get the derrick to haul up that pan.â

Frank looked at his brother. âHey, Jensent I could use a squarehead on this job.â

With Tonyâs help, the Hardys directed the crane operator to lift the huge vehicle. It needed a few repairs, which Tony handled with skill. While he worked, the three boys had a chance to confer.

Frank told the others of Yancyâs reference to the baron and added, âIf we could only get to him!â

âBut who is he, and where does he stay?â asked Joe.

Tony had not yet heard any reference to a person called the baron. âI donât think Biff and Chet have, either.â

âQuiet!â Frank warned.

A truck hauling rocks had drawn up close to the trio. A brawny man jumped from the cab, motioned Frank aside, and walked him out of earshot of Tony and Joe.

âWhatâs up?â asked Frank.

The truck driver looked him squarely in the eye and said, âHelix.â

Two thoughts flashed through Frankâs mind: Mr. Hardyâs mumbled word, which the boys had thought was Felix must instead be helix, meaning a spiral! And the warning received earlier by the Hardys was signed with a three-looped spiral resembling the letter M.

Frank deduced that âhelixâ must be the gangâs password, or at least a special sign used by them.

âOkay.â Frank made a spiral loop with his right forefinger and pointed upward. This seemed to satisfy the workman. He beckoned Frank again, moving farther away.

âWe got a job to do tonight, Teller.â

âA job? On whom?â Frank asked sharply.

âOn McGuire. Heâs been snoopinâ around like a dick, so heâs gettinâ a bath in the canal.â

Biff to be drowned? A wave of terror enveloped Frank, but he remained outwardly calm. âHow do I know thatâs true?â

âListen, If IâMike Shannonâsay so, itâs true.â

âOkay,â Frank said. âMcGuire thinks Iâm his friend.â

âGood. You and the Swede can take care of him at midnight.â

Frank trudged back to the pan, his mind in a turmoil. Biff Hooper was the next target of the gang. When Joe and Tony heard of the nefarious plan, they too were horrified.

âWeâve got to save Biff!â Joe said.

âWe will,â Frank assured him. âIâve got an idea.â

It was agreed that Tony would alert Biff later at an opportune moment, give him the plan of action, and warn him to show no surprise or emotion that night when the Hardys came to pick him up.

Outside the trailer after supper, Frank and Joe began a loud argument to provide distraction for Tony to speak with Biff. The Hardys disputed who could heave a rock the farthest. Chet, having been tipped off earlier, joined in the hassle. The three selected a round rock about the weight of a shot and started a contest. The men gathered around cheering as first one boy, then another took turns.

Even Deemer was intrigued. âI can do better than any of you!â he boasted. His put, several inches better than Chetâs, spurred others to enter the contest. Tony, after a few hurls, melted away from the crowd and disappeared behind his bunk trailer. Biff, having received the high sign from Frank, did the same. A few minutes later the two sauntered back to the âmeet.â

Meanwhile, Chetâs practicing paid off, and he became champ shot-putter a fraction of an inch over Deemerâs best hurl. Everyone cheered, but Angan said acidly, âIf you worked as hard with the pick and shovel, Ball, weâd get some work done around here.â

âYes, sir,â Chet replied meekly, and laughter drifted among the tall pines.

After sunset, darkness came on quickly and the trees loomed black against the fading daylight. Now the work camp took on a strange, foreboding hush which the Hardys had not experienced before.

Later, finding themselves alone in the trailer washroom, the brothers spoke in whispers.

âI wonder how many of these guys know Biffâs due for a bath in the canal,â said Joe.

Frank, drying his face, muttered through the towel, âMaybe only a fewâor maybe more. Thatâs the trouble. We have no idea how many are involved.â

In their bunks the two boys passed the time reading magazines. But all the while they had the strange feeling that the others in the trailer were furtively watching them.

At eleven-thirty Mike Shannon stepped inside and came over to Frank. âHereâs the tool youâll need for that job, Teller. In fact, maybe you and Jensen could fix it right now.â He slipped a blackjack into Frankâs hand and ambled out.

The brothers dressed, noting that the men appeared to be sleeping, undisturbed by Mikeâs visit.

Five minutes later the Hardys roused Biff from his bunk. âHey, McGuire, we got something to show you,â said Joe.

âAw, let me sleep,â Biff said, putting on an act.

âCome on, you big lunk!â

âOkay, okay.â Biff dressed and followed the Hardys outside. As the trio set forth, Frank noticed that Mike and another man were trailing them.

Biff feigned annoyance. âWhat are you jokers going to show me this time of night?â he asked loudly.

âYouâll see. Itâs down by the water,â Joe replied.

The boys made their way through the darkness, guided by the churning sound of the swift-running river. When they reached the edge of the water, the menâs footsteps grew louder. âQuick!â said Joe.

Frank drew back the blackjack and made a sweeping motion toward Biffâs head. With an anguished cry, Biff keeled over and fell, face down, into the rushing water.

âBoy, what a great act!â Joe whispered gleefully.

But his joy was short-lived. As he and Frank started to turn, the two men leaped on them! Each boy was dealt a heavy blow on the head. The Hardys reeled backward, unconscious, and tumbled into the torrent.

CHAPTER XIV

A Real Sacrifice

FRANK HARDY had the hideous sensation that he was caught in a maelstrom at the bottom of Niagara Falls. Tons of water crushed the air from his lungs, and his chest was constricted by a band of steel.

Then, as water swirled about his head, Frank regained consciousness. He was floating on his back, and the tightness around his chest was the strong arm of Biff Hooper.

âEasy, Frank. I got you.â

The boy felt himself being grabbed under both arms and pulled up on a stony bank. âYou all right?â Biff asked.

At first Frank could hardly speak. His head throbbed and he was half choking from the water he had swallowed. âJoeâWhereâs Joe?â

âI havenât found him yet. Donât worry. Heâll revive and make it to shore.â

Frank sat up groggily. âMan oh man, did those crooks ever double-cross us!â He rubbed his aching head and groaned. âThey mustâve found out who we were! You saved my life, Biff. Thanks! Now weâve got to find Joe!â

Frank struggled to his feet and staggered about, trying to gain his equilibrium. Finally his head cleared enough for him to walk without assistance. âWeâll follow the shore downstream, Biff.â

Pushing their way over jumbled rocks and through tangled brush which grew nearly to the waterâs edge, the two boys followed the course of the surging stream. Frank stumbled once, but pressed on, his jaw set with determination.

It was half an hour later when the two came to a gentle bend in the river. Silt had washed ashore forming a sandy crescent, and near the middle of it the searchers saw two prone figures. Biff ran ahead, with Frank plodding behind him. Drawing closer, they noticed that the pair were half in, half out of the water.

âJoe!â called Frank. âIs that you, Joe?â

Biff was already kneeling beside one of the figures when Frank stumbled to his side. The ghostly moonlight revealed the faces of Joe Hardy and Tony Prito !

Tony moaned, stirred slightly, then blinked his eyes. Frank at once applied mouth-to-mouth resuscitation to his brother. Tony, meanwhile, slowly sat up, gasping from exhaustion.

Finally Joe sucked in a great breath of air. His eyelids fluttered and he smiled wanly at Frank.

âHeâs okay!â Biff exulted, and set about briskly massaging Joeâs arms and legs.

It was not until fifteen minutes later that Joe and Tony felt equal to telling their story. Tony began. He had gone to the Hardysâ bunkhouse shortly after the two had left, and from the doorway, had seen Bond Deemer searching through the brothersâ belongings.

âDeemer didnât notice me. He exploded when he found your heavy sweaters!â Tony said. âThey had your name labels.â

âLeapinâ lizards!â Joe said weakly. âI know how that happened, Frank.â

âSo do I. We stuck âem in at the last second to please Aunt Gertrude and forgot to take the labels off. What goofs!â

Tony reported that he had trailed Deemer, who, furious at the deception, had passed the word along quickly to Mike and another man.

âI couldnât stop them from going after you,â said Tony, âso I followed, figuring I could help later, and posted myself downstream a short way.â

When he saw the Hardys fall in, Tony had swum to the rescue and reached Joe first. âI spotted Biff grabbing you, Frank.â

The Hardys expressed gratitude to their buddies. âWe would have been goners without you two,â said Joe.

âWhich reminds me,â Biff said dryly, âthe gang probably thinks the three of us are dead.â

âAnd I suppose theyâve got me pegged,â said Tony.

âThat leaves Chet alone,â said Frank. âHeâs the only connection we have left to Deemer and his mob.â

The four boys sat on the sand, discussing their next move. They all thought that Chet might have a chance to remain unsuspected of being one of the sleuthing team. Should they ask him to stay on the job as their only direct link with the ex-convicts?

âItâll be pretty risky,â Joe said. âWeâd better leave the decision up to Chet.â

Having agreed to this, the boys made their way farther downstream, crossed an old bridge, and edged stealthily back toward the construction camp. Joe had brought a waterproof flashlight, so the quartet had little trouble finding their way.

Tony, whose bunk was near Chetâs, volunteered to arouse him. While the Hardys and Biff waited in the woods, Tony slipped into the trailer. âKeep quiet and come with me,â he whispered. âHurry!â

Befogged with sleep, Chet groped after Tony in the darkness. When they joined the others, Frank and Joe recounted the latest happenings.

The chunky boy was now fully awake. âZowie, fellows! You sure had a close call!â He shifted uncomfortably. âGuess itâd be awfully dangerous to stay here alone.â

âYes,â said Frank. âThatâs what we were going to ask you about.â

âHmm.â Chet drew a deep breath and squared his shoulders.

âWell?â Biff prompted.

âIâll stay!â

âGood boy!â said Joe. âWe knew you would.â

The plan was to have Chet contact Phil Cohen at the Eagle Hotel in Boonton if anything important developed. âWeâll check with him later,â said Frank and added, âJust keep on working as usual, and keep your ears and eyes open.â

After handshakes all around, Tony returned with Chet to retrieve the Hardysâ radio and binoculars and rope from the cinder block. Chet was about to re-enter his trailer, when Tony said, âGot any food around, Chet?â

âWell, I did stash some awayââ

âAs usual.â Tony chuckled.

Chet disappeared inside and emerged carrying a paper bag. âThereâs bread and cheese in here,â he said. âA midnight snack I was saving. Donât say I never gave you anything!â

âYou mean take all of it?â

âEvery bit,â said Chet. âI better get back.â

When Tony told the others of Chetâs sacrifice, Joe whistled. âA real pal! Giving up his last bite!â

The four young sleuths pressed deeper and deeper into the woods. Finally they approached the area where the Hardys had seen the eerie rosy light in the sky. There the boys stopped and Frank contacted Radley by radio, giving him a full report.

The operative was stunned to hear what had happened to the Hardys and their friends.

âWeâre okay now,â Frank said. He asked Sam to have the Boonton police keep tabs on Yancy and any visitors at the hospital.

âAll right,â Radley said. âBut from what you tell me, I think we should close in on the mob immediately.â

Frank explained that first he wanted to find out who the baron was. âHe must be the ringleader,â Frank added. âBesides, we have to uncover whatâs behind the bridge sabotage.â

Radley reluctantly agreed to wait, but warned the boys to be extremely careful in their search for the baron. Sam informed the Hardys that their father was improving, but his memory remained unclear. Also, the prisoner Monk Smith had not yet talked.

âWeâll keep in touch, Sam,â Frank said.

âOver and out.â

âWhat next?â asked Biff.

Joe replied promptly, âGet some rest and start out at dawn to find the baron. He had scarcely spoken when a muffled blast in the distance filled the air.

âDynamite!â Tony cried out.

CHAPTER XV

A Lofty Lookout

THE blast was followed immediately by a rosy light which spread over the horizon like the aurora borealis. The glow lasted for five minutes, then disappeared.

âThatâs Rosy,â Frank said, recalling what Yancy had told him about the weird light. âIâll bet itâs some sort of trick to scare the superstitious hillbillies.â

âBut why?â queried Biff.

The Hardys both guessed that the strange phenomenon was designed by the criminals to keep the local people in a state of fear so they would not interfere with the gangâs project.

âWhatever that is,â added Joe.

âIf their leader can make that kind of magic,â Frank went on, âthink whatâll happen to anyone who defected or refused to obey orders.â

This line of reasoning interested Tony particularly.

âThen you think Rosy has something to do with the road and bridge construction trouble?â

âYes,â Frank replied, âbut the explosion puzzles me. I donât think it sounded like dynamite. I suggest we go on a hunt for Rosy after we get some shut-eye.â

By now the pink hue had died away. The weary foursome selected a sheltered spot, carpeted with pine needles, and flopped down. In a minute all were sleeping soundly.

The sunâs rays slanting into his eyes awakened Frank. He aroused the others, who stretched and yawned.

âI could have slept all day,â said Biff, standing up to flex his muscles.

âNot when we have a date with Rosy,â Joe quipped.

Biff came right back. âI wonder if sheâs as cute as Iola Morton.â

Scouting around for a few minutes, Tony found a rivulet of clear spring water. After a refreshing drink, the boys bathed their faces and hands. Next, Chetâs gift of grub was divided equally.

When they finished eating, the Hardys decided they should follow the trail which forked up the mountain, since the light seemed to have come from that general direction. Single file, the boys trudged up the slope, circumventing the bear cave.

Suddenly Joe stopped dead in his tracks. âFrank, look at that!â he said, pointing.

They all glanced to the top of the ridge.

âWhat do you see?â Biff asked.

âThe tallest pine tree right there in the center. Watch near the top.â

A moment later there was a glint as the sunâs rays bounced off a bright object.

âBinoculars!â said Frank.

âMama mia!â Tony burst out. âA lookout. The gang must have a hideout nearby.â

The boys agreed this would be the most likely place for the gang to post a sentry. A spy, high in the tree, could command a view of the valley and the entire road project. Anybody coming or going on the trail would be in the sweep of vision.

Frank cautioned everyone to walk parallel to the trail, careful to keep concealed among the trees.

âIt might be hard to find the tree when we get there,â Frank said as they neared the ridge. The young sleuths craned their necks but could not see the lookout.

When they reached the summit, the boys glanced in every direction. The boughs grew so thick that it was almost impossible to see the treetops in an unbroken line.

âAt least,â Joe said, âthe spy probably canât see us so easily. Thatâs some advantage.â

Frank guessed that they might have drifted too far to the south in their climb. âLetâs walk north along the ridge,â he suggested.

The boys spread out, inspecting one pine after another.

Biff, in the lead, waved wildly, signaling for silence. The others hurried to where he stood at the base of a towering tree. Biff pointed to an odd-looking cut, slightly higher than his head.

âGood night!â Joe whispered. âThatâs the spiral sign.â

The carving closely resembled what the Hardys had previously mistaken for an M with three loops.

âThis is our tree!â Frank whispered, and looked around at the other side of the trunk. âOh baby, see what I found!â

A set of spikes, hammered into the tree at regular intervals, provided footholds leading up among the dark branches of the evergreen.

Biff was jubilant. âWeâve treed the polecat,â he said. âLetâs climb up and sack him.â

âThat might not be so easy,â Tony said. âWeâd probably find ourselves taking a nose dive into the pine needles.â

Frank and Joe agreed with Tony. An assault from below could be dangerous. The person perched in the tree had the advantage of height. Also, he might alert the gang through a coded flash of some kind.

âMaybe theyâll change lookouts soon,â Frank said. âOur only hope is to wait.â

The boys posted themselves at various spots within a five-yard radius from the tree and began their vigil. Several times the twittering of birds and the warmth of the sun almost lulled them into drowsiness. Time dragged by.

Frank, rubbing his eyes to stay awake, caught the movement of a small piece of bark floating down from the big pine. He glanced up and saw that the branches far above him were shaking. Their quarry was climbing down. Frank sprang to his feet and signaled the others. The boys dashed behind a cluster of nearby pines and watched as a pair of long legs came into view, descending the spikes. Then, with both arms clinging to the trunk, a tall, gangling youth scrambled to the ground. Simultaneously, the Hardys and their pals leaped from hiding and seized him.

âWilly Teeple!â Frank cried out. The hillbilly looked half-frightened to death. He squirmed and struggled, but to no avail.

âWhat were you doing up there?â Frank asked.

âHeâs the long nit, donât you remember?â Joe put in.

âYouâyou know about that?â Willy quavered, shaking with fright.

âOf course we do,â Tony said.

âSure,â Frank went on, âthe helix too, and more.â

A look of earnest pleading came into Willy Teepleâs eyes. âLook! You fellows know too much,â he said. âGo away and donât come back.â

âWeâre going to stay right here,â Joe said, âand get to the bottom of this!â

âPlease donât,â Willy implored. âElse youâll get the same thing thatâthat happened to your father!â

The mention of Fenton Hardy electrified the boys.

âWhat do you know about our father?â Frank snapped.

âDid you have anything to do with what happened to him?â demanded Joe.

Willy shook his head, but would say no more about Mr. Hardy.

Both Biff and Tony were all for Willy being turned over to the Boonton police, but the hillbilly begged them not to do this.

âIf the boss knows youâve captured me, heâll hurt my father,â Willy went on.

âWhoâs your bossâthe baron?â Joe prodded.

Willyâs face went ashen. âI canât tell you.â

âWhat do you expect?â Frank said. âThat we just let you go?â

âI wonât fink on you, honest!â Willy Teeple said fervently. âI donât want to work for those crooks, but if I say any more, theyâll kill me if they find out.â

Willy swore again that he would not betray the Hardys and their friends. While Biff kept an arm-lock on their captive, Frank and Joe stepped to one side to discuss the matter.

âOkay,â Frank said, stepping forward. âWilly, weâll let you go, but donât say one single word about seeing us.â

Joe tried another question. âWhat about Rosy? Is that part of the gangâs scheme?â

Willy, terror in his eyes, remained silent. The boys did find out from him that the trail continued down the other side of the mountain and connected with a narrow road leading to Boonton.

âFellows, please go away from here. Itâs awful dangerous,â Willy pleaded.

At that moment there was a noise in the underbrush. The four boys ducked out of sight while Willy walked nonchalantly toward the sound. Mike Shannon stepped from the brush. The two merely exchanged nods; then, as Willy Teeple hastened back along the mountain trail, Mike climbed up the spikes of the lookout tree.

âWhat do we do about this guy?â muttered Biff.

âNothing yet,â said Frank. âWe still donât want to alert the baron.â

âI think we can trust Willy Teeple,â Joe said. âHeâs in the gangâs clutches, for sure.â

The four boys set off once more in search of a clue which might lead them to Rosy. As they headed down the opposite slope, Biff, who was in the lead, broke into a trot. Joe was close behind him. Suddenly Biff let out a cry of alarm and disappeared before Joeâs eyes!

CHAPTER XVI

Lower Than Pigs

JOE checked his speed just in time to keep from falling into a deep pit. Biff lay moaning at the bottom of the hole.

Frank and Tony ran to help Joe pull Biff out.

âOw! My left ankle! Itâs broken!â

Frank quickly examined the injury. âIt could be, but I think itâs only a bad sprain. Here, try to stand.â Biff made the attempt, winced, and nearly fell down.

âSomebody pulled a dirty trick,â Joe said.

The boys found that the freshly dug pit had been covered with boughs and a strip of tar paper, over which pine needles had been scattered.

Frank surmised that they probably were pretty close to Rosy, and that the trap had been placed there to discourage the curious.

After a hurried consultation, it was decided to get Biff back to Bayport as soon as possible.

âWeâll have you flown from the Boonton Airport,â Joe said. âPhil can go with you. Here, Biff, put an arm around my shoulder.â

With Frank and Joe on either side of their injured pal, Biff hobbled as fast he could. Occasionally Tony spelled each of the Hardys, until they reached the road leading to Boonton. It was gravelly and barely wide enough for two vehicles to pass.

âWe might have to wait all day for a lift,â Biff said, discouraged. Frank examined the injured ankle once more. It was so swollen that Frank removed the work boot. As he did, the sound of wheels drifted from around a bend in the road, and into view came a horse pulling a wagon loaded with pigs.

The driver, obviously a farmer, stopped when the boys hailed him. He was tall and gaunt, showing a thin, weather-beaten face in the shadow of his wide-brimmed hat.

âGoing to Boonton?â Joe asked.

âYep.â

âWould you give us a lift? Biff here is injured. Sprained his ankle.â

âAinât room enough.â

âPlease, Mr.ââ

âTeepleâs the name.â The man tilted his hat and jerked a thumb toward his pigs. âIâm going to market. Got a full load.â

Frank tried a long shot. âAre you Willy Teepleâs father?â

The question caught the man by surprise. âYou know my son?â

âSure, he works for the baron!â

âYou in that gang too?â the farmer asked, frightened, and Frank saw he was about to put the whip to the horse.

âWait, Mr. Teeple. No, we donât work for the baron, but we heard about him, on the road job. Do you know who the baron is, and where he hides out?â

The farmer grew agitated. âAll I can say is the baronâs a bad man. I donât know what heâs done to my Willy. But terrible things have been happening. Okay, the three of you get in back with the pigs. Iâll take the injured lad up front with me.â

Frank, Joe, and Tony pushed Biff up onto the seat beside Willyâs father. Then they jumped in with the pigs, and the wagon started toward Boonton.

âWhat are you boys doing here?â the farmer asked. âItâs dangerous.â

âWilly told us that,â Frank said. âWeâre looking for Rosy.â

âThe devil himself makes that fire!â the farmer exclaimed. On further questioning, he told the boys that several people, who had ventured near it, had vanished. âIncluding a detective!â

Before Frank could ask another question, a jeep appeared over the brow of a rolling hill, a mile away. Joe whipped the binoculars to his eyes.

âHere comes trouble. Four rough-looking customers and Iâll bet theyâre the baronâs men.â

âWeâll have to hide among the pigs,â Frank said. He grabbed Biff by the shoulders and pulled him into the back of the wagon. Then the four companions lay flat, with the pigs snorting and grunting and stepping over them with their cloven hoofs.

âThis isnât exactly a perfume factory,â Joe remarked.

âQuiet,â Frank whispered. âHere comes the car.â

With screeching brakes, the jeep came to a stop, alongside the farmerâs wagon.

âHey, you! Weâre looking for four guys. Have you seen âem?â

âWhat you say?â

âWeâre looking for four of our road crew. Theyâve stolen the payroll!â

âHay what?â

âOh, heâs deaf,â one of the men growled. âLetâs go.â

The jeep roared off, and when it was out of sight, the youths crawled from under the pigs.

âThanks, Mr. Teeple!â Frank said. âThat was a close call for us. And weâre not thieves.â

âI know it.â

The wagon crossed a small brook and stopped so the boys could wash and bathe Biffâs swollen ankle in the cold water. When they finally arrived at the airport, the Hardys and their pals thanked the farmer.

âDonât worry, Mr. Teeple,â Frank said. âYour son is okay. Weâre going to try to help him! But donât say a word about this to anybody.â

The farmer promised and the hitchhikers got out, assisting Biff gingerly into the terminal building. Joe immediately phoned Phil, asking him to check out of the hotel and hurry to the airport. Then the starved boys went to the lunch counter.

By the time they had finished three hamburgers apiece, Phil Cohen stepped out of a taxi and ran to greet them. After hearing their story, he said, âIâve got some news, too.â

Phil reported spying on four suspicious men staying at his hotel. âI heard them giving the password âhelixâ to the bellman,â he said, and pulled a sketch from his pocket. It showed the faces of the four men.

âI think theyâre the ones who were in the jeep,â said Joe. He took the sketch for future reference.

When Phil heard he was to accompany Biff back to Bayport, he asked, âWhat do we do for money?â

âFly now, pay later.â Frank chuckled, and hurried away to convince a charter pilot that Radley would pay the bill at Bayport.

After the two boys had winged off, Frank, Joe, and Tony went directly to the Boonton police station. There they inquired whether Yancy had had any visitors at the hospital. A lieutenant named Murphy reported that Yancy had had but one visitorâa seedy fellow who looked harmless enough. âClaimed to be a distant cousin.â

âDid you put a tail on him?â asked Tony.

Murphy said a patrolman had shadowed the man as far as a shack at the outskirts of Boonton. âIt convinced us that he was just a drifter,â Murphy continued, âso we didnât bother any further.â

The boys thanked the officer, got directions to the shack, and hastened to find it. It was located not far from the town dump, and was constructed of old planks and wooden packing cases. The makeshift roof, of corrugated tin, was full of holes.

The trio approached the rickety door of the windowless shelter. Frank listened. Silence. He opened it quietly and the three stepped inside.

âThis isnât exactly the Waldorf-Astoria,â Tony said with a chuckle. The shack was littered with empty bottles, tin cans, and stacks of old newspapers.

Frank and Joe immediately poked about the debris, looking for a clue to the mystery man. On the floor, poking out from under a moldy mattress, was a handle of a brief case. As Joe bent down to reach for it, footsteps sounded outside.

âHeâs coming back,â Frank whispered. âDuck!â

The boys hid behind a stack of cartons and listened. The footsteps came closer, then circled the shack. Finally the door opened slowly.

âOh boy!â a childish voice sang out. âHeâs not here today, either.â

âNow we can play detective club again,â a second voice chimed in.

Frank, Joe, and Tony stepped out from behind the boxes to see two young boys peering inside. They cried out with fright, turned, and fled.

âCome back here,â Joe called. âWeâre not going to hurt you!â

The youngsters stopped, then hesitatingly returned. âYou arenât robbers or anything?â asked the older one, who was about ten.

âOf course not,â said Joe. âSay, what are your names?â

The older boy was Andy Pulaski; the other, three years younger, was Rick. âWeâre brothers and we live on Church Street,â declared Andy. He said they often came to the shack to play, but a rough-looking man had scared them away several times.

âHeâs a bum!â Rick said, nodding his head vigorously. âI can tell, âcause he doesnât shave.â

âWell, you can play here all you want,â said Frank. He reached down and pulled the brief case from under the mattress. Then, leaving the boys to their fun, the young sleuths hastened away.

In the seclusion of a grove of trees, Frank and Joe stopped to examine the brief case, while Tony looked on.

Both sides were scorched and charred, and the place where initials would normally be imprinted was covered with dried mud.

Frank took out his knife and scraped away the crusty dirt. The initials showed up clearlyâF.H.!

CHAPTER XVII

Dangerous Terrain

âDADâs brief case!â Joe exclaimed. He opened it and looked inside. The case was empty, except for a gritty white substance in the bottom.

âLimestone!â Frank said, âCome on, fellows.â

On the double he led them back to the shack, where the two Pulaski youngsters were playing. Frank asked more questions about the man who had chased them away, but the children were vague in their descriptions.

âWhen he yelled âScram,â Rick and I just ran,â Andy said.

âHe scared me,â Rick added. âI didnât look back.â

Joe produced the sketches which Phil Cohen had made. âDid that fellow look like any of these?â he asked.

The children looked at the sketches and shook their heads.

âWell, if he comes back and chases you away again,â Frank said, âplease tell us. Weâll be staying at the Eagle Hotel. Ask for Frank, Joe, or Tony.â

âAre you detectives?â asked Andy.

âSort of,â said Joe.

âGee, weâd like to know how to be real detectives,â said Rick. âWill you show us someday?â

âMaybe,â Joe replied. âSee you later.â

Leaving the boys, Frank, Joe, and Tony made their way back to town. First, they stopped at the police station to report to Lieutenant Murphy what they had found and to leave the brief case there for safekeeping.

The lieutenant made a note of their investigation, saying he would be on the lookout for the vagrant. He added, âMaybe the old geezer found your fatherâs brief case somewhere. Doesnât mean he stole it.â

Frank agreed that they should not jump to conclusions, but said he still believed that the shack dweller must be considered a suspect.

âAnd what about this light in the sky called Rosy?â Joe asked.

âOh, that,â Murphy said with a shrug. âIâve never seen it myself. Who knows what to believe?â Chuckling, he added, âThese hill folks tell some awful tall tales.â

Frank told the police officer that they would be staying at the Eagle Hotel, in case any new leads turned up.

The boys went directly to the hotel, located two blocks from the station house. It was an old frame building with a small lobby. The boys registered as Frank Brown, Joe Jones, and Tony Wilson and paid in advance for one nightâs lodging.

âNo bags?â the clerk asked.

âWeâre traveling light,â Frank replied.

The clerk summoned the bellman, a stoop-shouldered and shifty-eyed individual. He led the boys to a room on the second floor, in which there were twin beds and a cot. After showing them the bath, the man left.

Meanwhile, the three boys plopped into their beds. But the next instant Frank jumped up and said, âThereâs something I forgot to ask Murphy.â He went to the telephone and had a call put through to the lieutenant. Frank questioned him about limestone deposits in the area. He was told that there undoubtedly were some in the caves and in a natural bridge deep in the woods.

âBut nobody goes there,â the officer said.

âWhy?â

âDangerous terrain.â

Frank was about to quiz Murphy further, when he heard heavy breathing on the line. Quickly he thanked the lieutenant and hung up.

âAn eavesdropper!â Frank said.

âThe bellman, Iâll bet,â Tony exclaimed. âPhil warned us about him.â

Joe bolted the door lock, while Frank switched on an antique radio atop the bureau. A shrill jazz tune welled up.

âNobody can overhear us now,â Tony said. âWhere do we go from here, fellows?â

âFind Rosy,â Frank said promptly. âIf we do, Iâm convinced weâll also find the baron. My guess is heâs behind that black magic.â

âFirst, I want a good, hot bath,â Joe said, stripping off his clothes.

He was in and out of the tub quickly. Tony followed. By the time Frank had finished toweling himself and stepped back into the bedroom, both Joe and Tony were sleeping soundly. Frank, too, stretched out, and despite the late-afternoon sunlight streaming in, he fell asleep as soon as his head touched the pillow.

The boys awakened to find it dark outside. Tony checked his watch. âNine-thirty! Did we ever need that sleep!â he said.

âAnd I could use some chow, too,â Joe declared.

They dressed and were about to leave when Frank suggested he and Joe take along the short-wave, the binoculars, and the rope. âJust in case somebody breaks in,â he said.

As the boys walked through the lobby, they noticed the bellman, his head tilted forward, apparently dozing. He did not stir as the trio passed. They found a diner several doors from the hotel, and had a hearty, though inexpensive meal.

âHowâs our money holding out?â Joe asked as Frank paid the bill.

âFor payroll robbers weâre pretty broke,â Frank quipped, then added seriously, âItâs time we phoned Radley.â

On the street once more, the sleuths found a public booth and Frank called Samâs number collect. Radley was not home, but his wife accepted the charges. She said that her husband had gone to the airport and met Biff and Phil. An examination by a doctor showed that Biff had, indeed, suffered a severe sprain.

The woman reported that Mr. Hardy continued to gain strength, but it would take time to overcome his lapse of memory.

âYour mother and Aunt Gertrude are fine,â Mrs. Radley added. âAny message for them?â

âTell them weâre okay,â Frank replied. âThanks, and good night, Mrs. Radley.â

Back at the hotel, the boys went quietly to their room. Frank turned the key, opened the door, stepped inside, and switched on the light. As he did, something white appeared from under the connecting door of the adjoining room.

Joe leaped to snatch it up. âA message!â he said, unfolding the sheet of paper. He read it aloud:

ââGet out! This is your last warning!â and signed âthe baronâ!â Joe held out the paper and they all saw beneath the name the now-familiar spiral sign.

Before the Hardys could stop him, Tony rushed out into the hall. In two strides he reached the adjoining room and tried the door. It was not locked, and he pushed it open. The room was pitch-dark. The light from the hallway failed to show any occupant. Tony slipped inside and felt for the light switch, but before his fingers could reach it, the door suddenly slammed shut. A brass-knuckled fist crushed against the side of his head and he went down in a heap!

A moment later the Hardys reached the closed door and pushed against it.

âSomethingâs propped against the other side,â Joe said.

He and Frank put their shoulders against the door and shoved it open enough for Frank to squeeze inside. He found the switch and flicked on the light. Frank gasped. Tony lay unconscious behind the door!

Frank ran to the open window, which opened onto a fire escape. Nobody there. He tried the connecting door to their room. Locked. Whoever delivered the note and the knockout blow had made a neat getaway.

The Hardys carried Tony back into their room, where he was revived with a cold compress. He stood up shakily.

âWhoo!â he said. âIâmâdizzy.â

âWeâd better get a doctor,â said Joe. âYou may have a concussion.â

Joe snatched up the sheet of paper

Frank decided to use a telephone outside the hotel, to call a physician and to report the attack to the police. He returned saying that a Dr. Jones was on his way.

All the boys were relieved when the examination indicated Tony needed only a few daysâ complete rest before resuming normal activity. When the doctor had left, the young detectives were in a quandary as to where Tony might stay.

âIt better be some place unknown to the baron,â Frank remarked.

âYouâre right,â said Joe. âThat gangleader is picking us off one by oneâdivide and conquer.â

âIâve got an idea,â Frank said. âHow about those two kids we met at the shack?â

âGood night,â Tony moaned, âI donât want to stay in that dump!â

âNo, not there,â Frank went on. âRemember Andy and Rick want to be detectives? Maybe their mother would put you up until you feel better. Meanwhile, Joe and I will look for Rosy and the baron.â

The Hardys thought they should leave the hotel at once. âOne attackâs enough,â said Joe.

Tony was able to navigate with the Hardysâ help, so the boys took their belongings and went downstairs. Nobody was in sight, not even the desk clerk.

Outside, they soon got a taxi and climbed in. The driver was familiar with Church Street and knew where the Pulaski brothers lived. He let the boys off in front of a modest, neat-looking house.

Frank rang the doorbell. A tall, lean man answered.

âMr. Pulaski? Sorry to bother you so late.â

âYes. What can I do for you fellows?â

Quickly Frank explained about Tony, without giving specific details of the mystery. He did say that he and his brother Joe were working on an important case.

âWe met your sons Andy and Rick,â Frank went on, smiling. âThey told us theyâd like to be detectives, so we thought maybe Tony could give them some pointers in exchange for your giving him shelter. Of course weâll pay youââ

Mr. Pulaski broke in. âDonât you worry about that. Be glad to help you out. Come on inside. My wifeâs right smart âbout takinâ care of sick folk.â

Mrs. Pulaski proved to be a cheerful, kindly woman. âWeâve got a spare room all ready,â she told Tony. âMake yourself at home.â

âThanks, maâam. Thatâs swell.â

Just then footsteps sounded on the stairway and Andy and Rick, in pajamas, scampered joyfully into the living room.

âI knew youâd all come back!â Ricky said. â âCause youâre going to show us how to be detectives.â

When they heard that Tony was to stay for a few days the youngsters were overjoyed. Frank now cautioned the family, âWeâd appreciate it if nobody else knows heâs here.â

The Pulaskis all readily agreed, eager to assist the young sleuths in the mystery. Sure that Tony was in good hands, Frank and Joe thanked the family and left. They walked through Boonton, found the road over which they had ridden in Teepleâs wagon, and began to hike back toward the wilderness. The night was cool and moonlight bathed the countryside.

Three miles out of town a panel truck rumbled up behind them and the boys thumbed a ride. The driver, an affable young man, took them to the place where they had met Mr. Teeple and the Hardys hopped out.

Using their flashlights, they found the trail over the ridge and made their way back to the dense woods. The boys kept a constant alert for the rosy glow, but the sky remained dark.

âGuess Rosyâs taken the night off,â Joe said as they carefully skirted the pit into which Biff had fallen. The trap had not been reset.

âWhat do you make of that, Frank?â

âThey think weâve cleared out.â

âBut what about other snoopers?â

âOh, I guess the baron thinks he has everybody else under control and scared. Just as well for us.â

The boys continued on to a spot not far from the trailers. There they stopped to rest.

âAs soon as possible, letâs talk to Chet. Maybe heâs found some new evidence,â said Frank.

The loud chirping of birds awakened the Hardys to a bright, hot morning. Nearby was a tall tree which they climbed for a better view of the road-building operation. Activity was already under way, as engines coughed and the various crews began their dayâs work.

Joe pressed the binoculars to his eyes. âI see Chet!â he said. âTake a look.â

Chet was shoveling dirt by the roadside, not far from the bridge. The Hardys shinned down the tree, then advancing cautiously on stomachs and elbows, edged closer for a better look. Now Frank had the glasses trained on Chetâs face. The stout boy kept glancing at the bridge, frowning. Finally he edged his way steadily to the span.

Suddenly Frank turned to his brother. âJoe, somethingâs up!â

CHAPTER XVIII

A Shot-put Blast

OBLIVIOUS of the fact that Frank and Joe were watching him, Chet Morton scrambled down the riverbank and peered under the partially completed bridge. The round, black object lying there intrigued him.

It appeared to be a kerosene flare, the kind which workmen use at night to warn passers-by of construction dangers. But the wick was not lighted. And wasnât it odd, Chet thought, that the bridge crew had not yet appeared?

Chet glanced at his watch. It was quarter past seven. Angan was always furious if work did not start at seven sharp. Chet looked up. There was the foreman himself, starting down the bank toward him.

âMaybe he knows about this flare,â Chet thought, and advanced to pick up the black object. He bent down and lifted it.

Tick-tick-tick-tick!

Like a bolt of lightning, the horrible truth struck Chet. This was no flare. It was a time bomb!

Chet was so paralyzed with fear that he could not even drop the menacing black ball. Instead, he ran toward Angan with it.

âMr. Angan! Mr. Angan!â

âWhat you got there?â

âA b-b-bomb!â

Angan froze like a statue. âA bomb! Get rid of it!â

Chet wheeled about and assumed his best shot-putting stance. And, with the ticking loud in his ear, he let the object fly! It was a record-shattering heave, sailing high over the bridge and landing downstream some fifty feet. Before the swirling current carried the missile twenty more feet, the air was rent by a deafening explosion. Rocks and debris shot high into the air, falling back into the water like giant hailstones. But the bridge was not damaged.

Chet Morton quaked with the shock. Speechless, he faced the foreman.

Angan roared, âWhereâd you get that bomb?â

âIâI found it under the bridge.â

âYouâre a liar! Same as Joe Jensen!â Angan lunged to grasp Chet, but the stout boy darted out of his way.

When necessary, Chet could move swiftly despite his weight and he sprinted up the riverbank toward the woods bordering the road construction.

âStop!â the foreman cried out, in hot pursuit. âStop, or Iâll have you arrested!â

Chet paid no heed. The Hardysâ faithful pal bulled through a thicket close to where Frank and Joe were hiding. Muttering dire threats, Angan charged after him. But his chase ended in a dull thud as he hit the ground with Joe Hardyâs arm clamped around his legs.

The foreman tried to rise, only to be pinned by Frank. Chet had glanced over his shoulder to see what the commotion was about. He retraced his steps, a look of surprise and gratitude on his round, perspiring face.

âWhereâwhereâd you guys come from?â

âExplain later!â Frank replied. âChet, you saved the bridge!â

âAnd thousands of dollars for Mr. Prito,â Joe added.

âLet me up!â Angan sputtered. He strained and tried to kick, but the Hardys held him down firmly.

âChet, grab that vine!â Frank commanded.

Chet pulled up a stout green tendril and handed it over. Frank and Joe deftly made loops and secured Anganâs hands and feet.

âIâll get you for this!â he threatened.

âThe gangâs already tried that!â Joe retorted. âAre you in with them, too?â

Without waiting for an answer, they left their trussed-up captive and melted into the woods.

Frank and Joe were unstinting in their praise for Chet.

The stout boy beamed with pride. âThat shot-putting stuff came in handy, eh?â

âSure did,â Joe remarked. âI think you broke the worldâs record, Chet!â

The Hardys headed for the mountain trail, and as they pushed on through the woods, they briefed Chet on their adventures and what had happened to Phil, Biff, and Tony. In turn, Chet told the brothers what new information he had learned.

âWord got around,â he said, âthat anybody who stepped out of line would be treated like you three guys. And they were sore when Tony disappeared.â

âIs the whole crew made up of ex-jailbirds?â asked Frank.

Chet replied that from what he had overheard, he judged only a handful of the men worked for the gang. âBut theyâre enough to keep the job slowed down and scare the other workers.â

âIf only we knew which ones are sabotaging the bridge,â Frank said.

Chet expressed the belief that despite Anganâs bad temper, he was loyal to the Prito company.

âDeemerâs a big wheel in the gang,â the chunky boy went on. âHe was really burned up when you fellows let the bear eat the honey.â

âSo he knows we did that,â Joe remarked. âWonder if that trap was his idea.â

âDoes Deemer know he didnât succeed in drowning us?â Frank asked.

Chet bobbed his head. âThey picked up your tracks in the woods, and I heard last night you were in Boonton.â

âThe baron has a regular spy network,â Frank observed. He and Joe were sure that the bellman had reported the Hardysâ presence. Chet had not learned anything about the baronâs identity, or the secret of Rosy.

âYou did some swell detective work, though,â Joe said.

The stout boy grinned. âI just eat and listen.â

âWhich reminds meâitâs nearly lunchtime,â Frank said, âand our stock is nil.â

âFear not,â said Chet. He reached into his bulging shirt pockets and produced three sandwiches. âI was saving these for coffee break, minus the coffee.â

The boys stopped near a brook, ate the sandwiches, and had a refreshing drink of cold, clear water. Afterward, the Hardys renewed their quest for Rosy. With Chet, they set forth up the mountain trail, giving the bear cave a wide berth. This time the boys did not cross the ridge, deciding instead to search the terrain south of the trail.

It was almost dusk when the trio paused to rest near a patch of wild blackberries, which they ate with zest.

âWeâd better find a good place to camp for the night,â Frank said.

All three scouted about until Chet came upon a shaded glen. Alongside it was a waterfall, which dropped in a foaming arch some ten feet into a deep, gurgling stream.

The boys cut branches for a lean-to, had supper of more berries, then settled back to watch for the rosy light in the darkening sky. Because all were weary from the dayâs tramp, the young sleuths took turns standing watch. Joeâs trick was ten until midnight. He sat with his back against a tree, desperately trying to keep his eyes open until the stroke of twelve. Once his chin bobbed against his chest, and he opened his eyes with a start. The night sky seemed brighter.

âFrank! Chet!â Suddenly the pink light mushroomed into the sky, with a brilliance which made the boys gasp. âRosy!â

âLeapinâ lizards!â Joe exclaimed. âItâs close by!â

Excitedly the trio scrambled out of the glen in the direction of the light. They crossed the stream and climbed to the top of a small knoll. The Hardys and Chet looked down in amazement at the scene below.

Out of a depression in the ground issued a stream of fire. Around it moved the figures of several men, their forms silhouetted against the glow.

âGood night! Whatâll we do?â Chet whispered.

âGet out of sight!â Frank commanded. âThe lightâs shining on us, too, you know.â

The boys ducked for cover, raising their heads now and again above the rise to take in the awesome sight.

Suddenly the flame diminished and disappeared.

âLetâs go back,â Frank said. âIf weâre caught prowling around here now, weâve had it!â

Despite their weariness, the Hardys slept little the rest of the night, wondering what the significance of their discovery was. Would it give them the solution to the mystery they had come to solve?

As soon as dawn tinged the horizon, the trio set off again. They advanced over the knoll and looked down to the spot where the great flame had been. There they saw a charred area, thirty feet in diameter. In the center of it, a black pipe protruded from the ground.

Chet Morton sniffed. âI smell gas!â

âMe, too,â said Joe.

The same thought dawned on all three boys at the same time. A gas well!

âJeepers! Why didnât we think of that!â Joeâs exclamation was punctuated by the sound of rifle-shots. Bullets thudded into the trees near the boys.

âRun for it!â Frank yelled.

As he and the others turned to flee, Mike Shan non and another man raced up the knoll.

âStop, or weâll shoot!â Shannon ordered. But the Hardys and Chet kept going.

They swerved sharply and plunged through a thicket. Their skin was scratched and their clothes torn by the brambles, but the barrier delayed their pursuers. More bullets ripped the twigs perilously close to the boysâ heads.

âTheyâll pick up our trail again,â Joe muttered. âWeâd better find a place to hide!â

âThe waterfall!â Frank said. âWe can hide behind it!â

Reaching the stream, the boys slashed into the water and made their way toward the churning falls. They burst through the curtain of water and stood chest-high in the swirling eddies.

âWhatâll we do if they look behind the falls?â Chet asked.

âDuck under,â Joe said, âand hold our breath.â

Just then two dark forms appeared on the other side of the opaque, watery screen.

âDown!â Frank commanded.

CHAPTER XIX

The Spiral Bridge

EACH boy sucked in a chestful of air and sank beneath the surface. How long could they hold out? All their athletic training came into play at this crucial moment. Thirty seconds. Forty-five. One minute! Their lungs ached for oxygen.

Frank swam underwater to the rocky wall behind the cascade. He had to surface! Coming up slowly, he scanned the watery chamber. Chet and Joe appeared at the same time.

âWe fooled them!â Joe whispered.

âYou think theyâll look here for us?â Chet asked.

The Hardys could not answer with certainty, but at least the shadowy shapes could not be seen through the tumbling screen of water.

âMaybe we ought to wait here a while,â Chet suggested.

âNot too long,â Frank said. âIf Mike Shannon and his pal think weâve escaped, nowâs our chance to turn the table and trail them.â

âThatâs right,â Joe agreed. âThey might lead us right to the baronâs hideout.â

The three sleuths let a few more minutes elapse, then Joe volunteered to be first out of the waterfall hideaway. He swam underwater, surfaced, and quickly reported back to the others that Shannon and his crony were nowhere in sight. The boys swam out cautiously, climbed out of the stream, and wrung the water from their clothes.

âLucky itâs a hot day,â said Joe. âWonât take long to dry off.â

Their field glasses were soggy but not damaged, and the short-wave, which Joe carried, was protected by a waterproof pouch.

The boysâ plan was to fan out in order to pick up the trail of their erstwhile pursuers. The Hardysâ bird whistle would be the signal if anyone came across the trail. The trio proceeded, still bearing south.

It was Frank who found the tracks made by the two men. Broken twigs and trampled underbrush told him that their enemies apparently had made no effort to conceal their route. Frank gave the whistle. Joe and Chet joined him on the run.

âRemember,â Frank said, âthese men are armed. Theyâll really let us have it if they spot us again. Weâll trail them, but be careful!â

It took only a short time for the boys to catch sight of their quarry. Shannon and his partner were climbing over a jagged outcropping on a steep, rocky slope. The ground ahead was rough and uneven, and the Hardys recalled Lieutenant Murphyâs statement about dangerous terrain.

The boys waited until the men had disappeared over the crest of the hill.

âOkay,â whispered Frank. âLetâs go.â

Exercising utmost stealth, the boys advanced to the slope. Loose stones and shale underfoot made the ascent a difficult one. A misstep could mean a landslide, or painful fall. Finally the Hardys and Chet reached the top. Below was a long valley, creased by a placid stream. Spanning this was a natural bridge of great beauty, resembling a noble arch.

The men were just nearing the span. Suddenly they vanished!

âThey didnât go under the bridge or around it!â Chet said.

Frank and Joe studied the formation through the binoculars. It was obviously composed of limestone, about fifteen feet thick. The left side of the bridge jutted out from high ground, then curved gracefully to the right, down amid a jumble of boulders at the level of the brook about seven yards from shore.

Crawling from bush to bush, the boys drew closer to the bridge. Frank stopped to study it again with the field glasses. Now he saw that in the center of the arch, on the underside, there was an opening the size of a manhole, through which water dripped into the stream below.

âChet, you stand as a lookout,â Frank said, âwhile Joe and I scout around the bridge. These crooks must have a hideout nearby. If you see anyone coming, give the bird whistle.â

Chet concealed himself behind a thicket, while the Hardys darted from bush to tree as they moved toward the lower side of the natural bridge. There they examined the crevices among the boulders, but did not find an opening.

Since there was no warning from Chet, Frank and Joe boldly struck across the shallow water and climbed the slope to the top of the bridge. Carefully they walked onto the flat surface.

âLook at this.â Joe pointed to a small trickle of water which seemingly vanished into a small hole in the rock.

âThat explains it!â

âExplains what?â

âThe water coming out of that hole underneath,â Frank replied. He reasoned that the tiny rivulet, over thousands and thousands of years, had cut into the limestone bridge and gouged its way out underneath.

Joe snapped his fingers. âFrank!â he said quietly. âDo you suppose this whole bridge could be hollowed out by water erosion?â

Frank shrugged. âCould very well be.â

The boys returned to Chet and told him what they had found.

âWhat a great tourist attraction!â Chet declared. âBoy, Iâd like to have the concession for a soda pop and hot-dog stand!â

âNo doubt.â Joe groaned. âChet, you would have to talk about food when we havenât a crumb to eat!â

âCut the chatter,â Frank warned. âThose crooks might be listening to us right now.â In low tones he urged that they scour every inch of ground around the natural bridge. âMike and the other man didnât just vanish by magic!â

It took until late afternoon before Joe stumbled upon a clue. He noted that a number of branches had been freshly cut from a willow tree.

âYou think they were used for camouflage, Frank?â Joe asked.

âThatâs my guess,â Frank said. âTheyâre hiding something.â

âCome on. Weâve got to find it,â Joe said excitedly.

The rays of the sinking sun were filtering through the treetops, casting an oblique light on the forest floor. It was then that a glint caught the searcherâs eyes. It showed through what appeared to be a thicket, but on closer examination the Hardys found a cleverly rigged bower of willow boughs.

Tensely the boys parted the greenery and peered into the depths. The glint shone from the steering wheel of a jeep! âThe same jeep we saw coming from Boonton!â Joe exclaimed.

The boys found that the vehicle bore a license number, but otherwise no identification. The Hardys, however, noted that the hiding place was close to the right-hand base of the natural bridge, with the car facing the rock pile.

The trio posted themselves near the camouflage for an hour, but nobody appeared. Soon it grew dusky and the boys retreated downstream to observe the bridge. As darkness fell, Chet suddenly pointed to the underside of the span. âFrank! Joe!â he said excitedly. âThereâs a light coming from that hole!â

âSomebodyâs inside!â Frank turned to his brother. âJoe, your guess about erosion really zeroed in! The bridge itself is the gangâs hideout!â

But how to get inside? Frank finally came up with a plan. âThere must be an opening among those boulders. Joe, you and Chet look again. Iâll stand guard here.â

Joe left the binoculars, a flashlight, and the radio with Frank. Also the nylon rope, which he had carried looped from his belt.

The light from the rising full moon helped guide Chet and Joe to the other side of the brook and the rocky base of the arch.

This time even the surface of each boulder was examined carefully. One after another proved to be hard and firm, with no hint of a possible crevice entranceway.

Suddenly Chet beckoned excitedly to Joe, who scrambled over.

âLook!â Chet whispered. He pointed to a yawning hole near the bottom of a huge boulder. âI can just squeeze through it!â

Joe put his ear to the opening. The sound of menâs voices echoed dimly from inside.

âLetâs get Frank!â Chet said.

âWait,â Joe whispered. âIf we can case this layout, itâll be a big help to the police.â

Reluctantly Chet agreed. âLead on,â he said with a resigned sigh.

The narrow opening quickly gave way to a tunnel which was head-high. Joe and Chet stood up and listened. When their eyes became accustomed to the dimness, the boys felt their way upward along what proved to be a series of looping curves.

A thought struck Joe. âSure!â he said aloud. âThis passage is like a spiral! That explains the helix password. Dad must have discovered this natural spiral bridge just before he was captured!â

Chet opened his mouth to reply, but never did. Suddenly two men sprang toward them from tall niches on either side of the rock wall.

Joe and Chet, caught off balance, struggled violently but in vain. Ropes bound their arms to their sides and they were pushed roughly along through the spiral interior. Here and there, kerosene lanterns, fastened to the wall, lighted the sinister faces of their captors. Neither was familiar to the boys. âWe got you pests for good this time!â snarled one. âYour luckâs run out.â

âIt sure has, Pete,â the other chortled.

By now they were at the top of the arch where the tunnel leveled off. The captive sleuths were shunted into a small side chamber, carved out of solid rock. The light from several lanterns showed the place to be a veritable arsenal with weapons of all types hanging on the walls, and around a rough-hewn table in the center sat four menâthe same men who had been riding in the jeep the other day.

Another man, tall and gaunt-faced, stood lounging in the shadows against the far wall. When he came forward into the light, Joeâs jaw dropped and he stared at the man in utter disbelief.

âMortimer Prince!â The vagrant Frank and Joe had met in New York!

As Joe watched, half-dazed, Mortimer Prince moved to the head of the table and sat down. The thug called Pete stepped up and addressed him with an air of great self-satisfaction.

âWe got the Hardy boys. Whatâll we do with them, Baron?â

CHAPTER XX

Swinging Tactics

JOE blinked in astonishment. Mortimer Prince was the baron! The gangleader rose from the table, his face contorted in fury.

âFools!â Prince stormed at the two henchmen. âYou only got Joe Hardy. This fat boy is not Frank!â

Pete looked frightened. âFerd and I thought we had âem both.â He pointed to Chet. âYou sure he ainât Frank Hardy?â

âI know the Hardys!â the baron shouted. âGet going and nab Frank!â

Ferd and Pete scurried out of the rock-hewn chamber. In an undertone Joe rapidly told Chet that the baron was the bum that he and Frank had encountered in Manhattan. âShut up, you two!â the baron ordered.

âWho are you, anyway?â Joe asked boldly. âAnd what kind of racket are you up to?â

âNever mind. Itâs enough for you to know that Iâve outsmarted Fenton Hardy and his sons!â

âYouâre the one who nearly killed my father!â Joe said angrily. âWhy?â

The baronâs eyes held a cruel glint. âThat old man of yours sent me up the river twice!â

One of Princeâs henchmen said menacingly, âNobody can do that to the baron. It means curtains!â

Chet went white as a sheet, and Joe felt a tingle of fear up his spine. If Frank could only get away! Meanwhile, Joe decided to try stalling for time.

âThose ex-cons working for you now,â he said, âarenât following your orders to sabotage the road construction just for laughs.â

âThatâs right.â The baron was obviously pleased with himself. âOnce you and your nosy pals are out of the way, Iâll put the kibosh on Pritoâs job permanently.â

Chet found his voice. âYouâll never get away with it.â

âHa-ha! Listen to fatso!â came Mike Shannonâs sneering voice as he entered. âThis time you punks are all washed up.â

Joe ignored him and shot another question at the baron. âAre you trying to prevent the road from being built because of those natural gas wells?â

A mocking expression crossed the baronâs face. He bragged that one of his men had found the gas deposit by accident. Now the baron was scheming to buy the land at a ridiculously low price.

âMeantime,â he added gloatingly, âI have a pipe down there with a valve on it. When we light the gas at night, it scares the devil out of people around hereâkeeps âem from snooping.â

Joe queried him about the explosion the boys had heard after seeing Rosy. The baron smirked. âThat was because of faulty ignition.â He went on to say that the new county road would bring too much traffic near the gangâs unique hiding place in the spiral bridge. He was determined that the road construction would not be completed until he had secured the land with the gas deposit.

The boys learned from the baron how Willy Teeple had been forced to work for the gang. âI just remind Willy that if he squeals on us, his father will get the same treatment as Fenton Hardy.â

The baron went on to describe the detectiveâs capture. He had been waylaid by several of the gang near the gas well, where his scorched brief case had been found later by the baron.

âAfter that everything was simple,â Prince said smugly. âWe put Hardy in our special dungeon here. Foolishly he tried to break loose but weâerâdiscouraged him.â

Joe clenched his fists. âHe still managed to escape from you rats!â

âHe must have pulled a Houdini act.â The baron shrugged. âBut heâs through as a gum-shoe.â

âBaron,â Joe said, âyou should give up. Youâre a two-time loser. Next time youâll go to prison for life.â

âThere wonât be any next time,â said the baron. âBy the way, I intend to spring Monk Smith after we take care of you kids!â

The other men guffawed. âWeâll bury the evidence, wonât we, Baron?â one said with a meaningful look at the captives.

At that moment Frank Hardy was busy eluding the two henchmen, Pete and Ferd. He had seen them emerge from the boulder entrance, and surmised that Joe and Chet were in the hands of the criminals. Frank had quickly hit upon a plan.

As the two men ranged farther from the bridge, Frank crept up to the camouflaged jeep. On the floor he found a toolbox and took out a stout screw driver and a small sledge hammer. Next he opened the hood, and, groping in the darkness, finally managed to jump the wires to the ignition. The engine turned over and chugged to life.

Carrying the tools, Frank scrambled with desperate speed onto the top of the stone bridge directly over the hole underneath. He found a small fissure into which he inserted the screw driver, and tamped it as quietly as he could into the soft limestone rock.

Then the young sleuth tied one end of the nylon rope around the makeshift piton. The other end he secured tightly to his belt.

âThis is my only chance,â Frank thought, his heart pounding.

He grasped the rope tightly and let himself down toward the underside of the arch. Now came the crucial moment. He pushed hard against the rock with his feet, at the same time paying out ten feet of rope. The result produced a pendulum motion.

Swinging back and forth, Frank aimed for the hole. Could he make it? Twice his feet missed the opening by inches. On the third try Frank succeeded, and with a jackknife movement, pulled himself up into the bridge.

Exhausted, Frank flopped onto the stony floor. But a moment later he untied the rope from his belt and weighted the end with a heavy stone. Frank set forth through the passageway, dimly lighted by kerosene lanterns on the wall.

Although his main concern was whether or not his decoy trick with the jeep would work, Frank noted the spiral shape of the corridor. The helix sign flashed through his mind just as a voice echoed hoarsely down the passage. âHey, the jeepâs runninâ!â someone yelled.

Frank crouched in a deep rocky niche and heard heavy footsteps pounding on the stone floor. When he was certain the men had gone outside, Frank proceeded until he came to a side chamber hollowed from the rock. Inside he saw Chet and Joe.

âFrank!â Joe exclaimed. âHowâd you get hereâwhatââ

âTell you later. Hurry!â

Their arms still bound to their sides, Chet and Joe followed Frank to the hole in the bridge. Frank whipped out his knife, cut their bonds, and whispered. âThe fireworks should start any minute. When they do, weâll slide down the rope and drop into the stream.â

No sooner had he spoken than a volley of shots filled the air. âTheyâre firing at the jeep. They think someoneâs trying to steal it. Come on!â

Chet was first down the rope, Joe next, then Frank. They slipped into the stream and swam quickly to cover on the far bank. They could see flashlights winking on and off in the woods like fireflies, and then, abruptly, the gunfire ceased.

The silence that ensued was almost uncanny. Cautiously the Hardys and Chet crept from concealment toward the flickering lights. The scene that met their eyes made them gasp in amazed relief and joy.

Held at bay by a force of law officers, mostly State Police, were the baronâs men! Accompanying the police were Tony, Willy Teeple, and Robert Angan, the foreman.

âThe baron got awayâdisappeared!â Tony shouted upon seeing his three pals.

Frank pointed to the stone bridge. âHeâs probably inside.â

A tear-gas bomb was lobbed through the hole. Soon the baron, choking and begging for mercy, staggered into view.

The Hardys and their pals clapped one another on the back and exchanged stories. âTony, how did you and the posse find this hideout?â asked Frank.

âI just couldnât stay put when I suspected you fellows were in danger. Besides, I feel okay now.â Tony explained that he had spotted Willy Teeple in town and pleaded with him, for the Hardysâ sakes, to reveal what he knew about the gang. The two boys then had persuaded the Boonton police to round up a search force.

First, the lawmen had gone to the road construction site, where members of the gang, including Bond Deemer, were placed under arrest.

âWe got here just in time to hear the shooting,â Tony said.

Standing among the captured gangsters was the bellman from the Eagle Hotel. He readily admitted eavesdropping on the boys and conking Tony. The Hardys and Chet related to the police what the baron had told them of his activities. Lieutenant Murphy stepped forward and praised the boys for their clever sleuthing.

âYouâve made a big catch,â he added, indicating the baron. âThatâs really Gerald Thurston, master of disguises! He was the âcousinâ who had visited Yancy in the hospital.â

Joe whistled. âIâll say! Intern, housebreaker, and bum!â

Thurston glared balefully at the Hardys but said nothing. Frank, Joe, Chet, and Tony were also congratulated by Angan. âThe road crew owes you a lot,â he said gratefully, and Willy agreed vigorously.

The next day the boys flew back to Bayport. When Frank and Joe reached home they found their father resting in his room.

âDad!â said Joe. âItâs great to see you looking better!â

âTerrific job, fellows!â Mr. Hardy said.

Frank beamed. âThanks. Iâm glad we could pinch-hit for you. But weâre still puzzled about a few things.â

The boys took seats near Mr. Hardyâs bed and the detective told his story. Before setting out for Kentucky, he had pulled two cards and dossiers from his files, Matlackâs and Thurstonâs. When the baron had found Mr. Hardyâs brief case, he discovered the records inside. He had promptly flown to Bayport, gone to Radleyâs home and stolen Matlackâs card, knowing that Frank and Joe would check their fatherâs duplicate file. Mr. Hardy smiled at his sons.

âWhen your pursuit of Matlack ended in the Queens graveyard,â he said, âThurston figured youâd be discouraged and give up the case.â

âHey!â exclaimed Frank. âNow I get it!â He hurried into his fatherâs study and opened the files to the Tâs. Thurstonâs card was gone, and there was a memorandum in its place saying, âI suspect Matlack or Thurston, but because of his M.O. I think Thurston is our man.â

Frank burst into his fatherâs room, waving the card. âDad, what a terrific deduction!â

Mr. Hardy explained that Thurston had written him threatening letters while in prison. âWhen he was released, I suspected heâd make trouble for me if he ever had a chance.â

âHe sure did!â Joe said grimly.

Frank asked his father how he had escaped from the dungeon in the spiral bridge.

âWilly Teeple helped me at great risk to himself,â said the detective. âOne day the gang left Willy as lookout at the bridge. He unlocked my handcuffs and assisted me to the road, where Mr. Teeple gave me a ride to Boonton. Willy put the handcuffs on me again so the baron would not suspect him of defecting.â

Frank and Joe, pleased that the mystery was solved, wondered if another as exciting would come their way. They were soon to find out when challenged by The Secret Agent on Flight 101.

At this point, footsteps were heard on the stairs and into the room trooped Mr. Prito with Tony, Chet, Biff, and Phil.

Everyone cheered when Mr. Prito announced that since the Kentucky wilderness would be opened up by the completion of his road project, plans had been made to develop the natural bridge as a main tourist attraction of the proposed park.

Joe grinned. âYou still going to open up a hot-dog stand down there, Chet?â

The chunky boy groaned. âNo more spiral bridges for me. Iâm going to stick to something safe, like shot-putting!â