The "Seacat" Clue

Franklin W. Dixon

Hardy Boys Mystery Stories: Volume Nineteen

The Disappearing Floor

Copyright, 1964, by Grosset & Dunlap, Inc

This is the revised 1964 text

Once again Frank and Joe Hardy take on a puzzling case when their famous detective father asks the boys to assist him in tracking down a notorious jewel thief and his accomplices. The trail leads to the outskirts of the Hardys home town and to a weirdly guarded mansion on the old Perth estate. With their pal Chet Morton, the brothers must tackle the mystery of the mansion heir’s sudden death. A disappearing floor, a huge, savage-looking, hound, a galloping ghost, and a college professor’s startling invention are just a few of the strange elements that complicate the boys efforts to solve both mysteries.

CHAPTER I

Weird Screams

"HEY, Frank! Isn't that the black car Dad told us to watch for?" exclaimed Joe Hardy.

A sleek foreign sports car with a dented trunk had just whizzed past the Hardy boys' convertible as they drove through the downtown section of Bayport.

"Sure looks like it!" Frank speeded up in pursuit.

Dark-haired Frank Hardy, eighteen, and his blond brother Joe, a year younger, had been cruising the streets on an errand for their detective father. The August evening was warm, and the boys had put down the top of their convertible.

A few blocks farther, the sports car stopped for a red light. The Hardys pulled up behind the trim vehicle. In the glow of a nearby street light they were able to scrutinize the automobile more closely.

"That must be the right car," Frank, muttered. "It's not likely there would be two of the same model in Bayport with dented trunks."

The lone occupant of the sports car was the man at the wheel. He wore a dark hat. Frank and Joe could see only the back of his head.

"Did Dad give you any details on the case when he phoned?" Joe asked, as the sports car spurted forward on the green signal.

Frank toed the accelerator and shook his head. "No, he didn't have time–it was just a hurried call from New York." Mr. Hardy had said that before leaving Bayport he had spotted a car like the one the boys had just seen. He thought he had recognized the driver as a notorious jewel thief named Noel Strang, and had told his sons to look up the criminal's photograph in Mr. Hardy's private criminal file.

The boys' father formerly was an ace detective in the New York Police Department. He had moved to the town of Bayport to open his own agency and soon had become known as the ablest private investigator in the country. Frank and Joe had inherited Fenton Hardy's detective abilities and often helped him on his cases.

The boys drove on, staying behind the sports car which now sped into a residential area. The streets here were less well lighted, but the boys were able to keep their quarry in view without tailing it too closely.

"Looks as though he's heading out of town," Joe remarked.

"Did you get the license number?"

"Yes. I jotted it down at the traffic light."

In a few moments the black sports car shot out of the Bayport area. Soon it disappeared from view around a bend in the road. Frank switched off his headlights, hoping to make the convertible less noticeable. But the driver of the other car seemed wary of pursuit. As the convertible rounded the bend, its driver increased his speed. The distance between the cars was widening.

"He must have spotted us!" Joe said.

"He's sure opening her up," Frank agreed. "That baby looks powerful! Good thing we tuned up this engine last week."

The convertible's speedometer needle rose as Frank gunned the engine. Slowly the gap began to close. They were approaching another bend in the road. Suddenly the sports car's exhaust belched out a thick purplish mass.

"It's a smoke screen!" Joe cried out. "He's using a fogger attached to the exhaust pipe!" A split second later the boys' eyes began to smart and water.

"Good night!" Frank exclaimed.

Hastily he switched on their headlights again, but the beams could not pierce the thick pall of acrid smoke that enveloped the road. The convertible was almost at the sharp bend!

Frank slammed on the brakes. Half blinded, he could only guess at the location of the white line. He spun the steering wheel and the car slewed wildly across the pavement. With a jarring thud it finally came to rest on the far shoulder of the road.

"Jumpin' jiminy!" Joe sat quivering with shock, trying to steady his nerves.

Frank, also shaken, drew a long breath. "Good thing there was no car coming the other way or we'd be junk by now!"

"Can we risk getting back on the road?"

"We'd better not," Frank decided. "I can't see a foot away from us. If there's any traffic coming, we'd be asking for a crash."

Joe agreed and added, "Let's make sure we're clear of the pavement."

Clutching handkerchiefs over their noses and their tear-streaming eyes, the boys climbed out. In the smoke and darkness, it was impossible to determine their exact position, but Frank checked with his foot and found that they were well off the pavement. The convertible had landed against a hillside bordering the road.

Frank and Joe chafed at the delay, but there was nothing to do except wait for the smoke to clear. Meanwhile, they clambered up the hillside, coughing and choking, to reach clear air.

"Did you notice the smoke's color?" Joe gasped. "That was no ordinary smoke screen!"

"Right. Sort of a combination of smoke and tear gas."

After a few minutes the murk had dissipated enough for the boys to return to their car and swing back onto the road.

"Not much chance of finding that man now," Joe said glumly.

"Let's keep our eyes open, anyhow. There are houses along here and a few turnoffs. We might spot the car parked somewhere."

The Hardys followed the road for several miles but did not see the sports car. Disappointed that they had lost their quarry, Frank and Joe turned around and headed for Bayport.

Halfway back to town, they saw a flashlight being waved frantically from the roadside. "Wonder if there's been an accident," Frank said.

"I don't see any car," Joe replied. "Must be a hitchhiker."

Frank slowed to check. The person who was signaling immediately jumped into the glare of their headlights. He was a chunky, round-faced youth about their own age.

"Chet Morton!" Joe exclaimed in surprise.

The stout boy looked excited as he flagged them down. Frank braked to a halt and Joe flung open the car door. "What's wrong, Chet?"

"Joe! Frank! Boy, what a lucky break you two happened along!" Chet was puffing and trembling and looked pale. He was wearing hiking shorts and had a knapsack slung over his shoulders.

"Just see a ghost?" Frank asked as their friend climbed into the back seat.

"I d-d-didn't see a ghost-but I sure heard one!" Chet replied.

Frank and Joe exchanged puzzled looks. "What do you mean, you 'heard' a ghost?" Frank asked.

"Just what I said. It screamed at me." Chet shuddered. "O-oh, it was horrible!"

"Are you kidding?" Joe put in.

"Do I look as if I'm kidding?"

"No," Frank said. "You look as if you'd been scared out of your wits. How about telling us the whole story?"

Chet explained that he had been on a rock-collecting hike. Late in the afternoon he had stopped to eat a picnic snack and then had dozed off.

"Snack my eye!" Joe chuckled. "You probably stuffed yourself so full you couldn't move, and dreamed about this ghost."

"All right, all right," Chet retorted indignantly. "So I like to eat. Do you want to hear my story or don't you?"

"Go ahead," Frank urged.

"Well, I slept longer than I expected to," Chet went on. "When I woke up, it was dark. I was somewhere over in the hills west of here. I had trouble finding my flashlight. Then I saw a funny-looking tiled surface."

"Tiled surface?" Joe repeated. "What do you mean by that?"

Chet shrugged. "I don't know what else to call it. It was flat-like a floor, about ten feet square and inlaid with little colored tiles. But the funny thing is, there was nothing else around except trees and shrubs."

The colored tiles, Chet added, formed a curious design resembling a dragon.

"I went over to get a closer look at it," Chet continued, "and wow! Out of nowhere came a horrible bloodcurdling shriek!"

"So you scrammed, I suppose," Frank said, grinning.

"You bet I did! The voice shrieked after me, but I didn't catch what it said." Chet's eyes bulged with fright at the recollection. "I kept running till I hit a dirt lane, and followed that out to this road. I was hiking home, then you guys came along."

"How about taking us back there?" Joe said.

"You think I'm nuts? Honest, if that wasn't a spook, it must have been some bloodthirsty lunatic!"

"Oh, come on!" Frank urged. "Maybe it was just someone playing a trick on you. Let's find out."

Chet was unwilling, but finally gave in. He directed Frank to a dirt lane turnoff which the Hardys had passed about fifty yards back. Frank drove slowly along the lane until Chet said, "Right here! I remember that big oak tree!"

Frank stopped the convertible. The boys took flashlights and climbed out. They went up a slope which gradually flattened. The area was wooded with hemlock and cypress trees, and the ground between them was overgrown with weeds and brush.

"There's Chet's trail," Joe said, shining his flashlight on some trampled grass. "It leads over that w-"

A hideous scream split the darkness! Then came a weaker scream, followed by a hoarse, croaking voice. "Th-th-the floor!" It sounded like the gasp of a dying man!

Chet froze in terror, but Frank and Joe immediately ran toward the sound, playing their beams back and forth amid the undergrowth.

"Over here, Joe!" Frank exclaimed suddenly.

Joe ran to his brother's side and saw a man lying face down on the ground. Frank turned him over gently. The man was big and balding, with thin, sandy-colored hair. His face looked deathly pale. Frank tried his pulse as Chet came lumbering up.

"Is he d-d-dead?" Chet stammered.

"No, but his pulse is weak," Frank murmured. "His skin feels clammy, too. Looks as if he's suffering from shock."

The Hardys could detect no signs of injury or broken bones.

"What'll we do with him?" Joe asked his brother.

"Better get him to a hospital."

The boys carried the limp figure to their car and laid him on the back seat. Chet sat up front with the Hardys. Frank swung the convertible around and sped toward Bayport.

As they reached a wooded area on the outskirts of town, their passenger revived and sat up. "Please-stop the car!" he begged weakly.

Frank pulled over. "We were taking you to the hospital," he explained.

"You were unconscious," Joe added. "What happened?"

"I'll–I'll tell you in a moment," the man said. "Right now I feel woozy. I think the motion of the car was making me sick. Would you mind if I get out and walk up and down a bit?"

"No-go ahead," Joe said sympathetically.

Chet leaned back and opened the door. As soon as the man's feet touched the ground, he slammed the door. His face contorted into an ugly expression.

"If you boys know what's good for you, you'll keep your mouths shut about this!" he snarled. "And I'm warning you-don't try to follow me!"

He darted off into the darkness of the surrounding trees!

CHAPTER II

Telephone Tip

THE three boys were stunned by the man's unexpected threat and actions.

"Of all the creeps!" Chet spluttered when he found his voice. "How's that for gratitude?"

"I'm going after that guy!" Joe exploded. He yanked open the door and started to jump out, but Frank stopped him.

"Hold it, Joe! You'll never catch him now. Besides, he may be armed."

Joe realized the wisdom of his brother's advice and reluctantly climbed back into the car. The neighborhood was run down. It was poorly lighted and had numerous vacant lots and small factory buildings. The stranger already was out of sight and doubtless could find plenty of hiding places if pursued.

"I'd sure like to know what that fellow was afraid of," Joe muttered as they drove off. "Also, how he came to be lying back there, unconscious."

"So would I," Frank said. "We'd better notify the police."

"Look, fellows, I-uh-I'm pretty tired," Chet said uneasily. "Could you drop me off home first?"

"What's the matter?" Joe teased. "Afraid the police may hold you as a suspect?"

"I told you I'm bushed!" Chet retorted. "Besides, you Hardys are always getting mixed up with crooks and mysteries. That kind of stuff makes me nervous!"

Frank and Joe grinned in the darkness. It was true that they had worked on a number of exciting cases since their first one, The Tower Treasure. On their most recent adventure they had solved the mystery of The Twisted Claw.

After dropping Chet off at the Morton farm, the Hardys drove to Bayport Police Headquarters. Here they found Chief Collig working late. The husky man smiled broadly as they walked into his office.

"You boys busy on another case?"

"We're helping Dad," Frank explained. "But something else came up." He told about the unconscious man who had later revived in their car and fled after threatening them.

Collig agreed that while the episode was strange, apparently no crime had been committed. He telephoned the fugitive's description to the police radio dispatcher to be flashed to all prowl cars, with orders that the man be picked up for questioning.

Frank told him about the boys' pursuit of the black sports car and the smoke grenade that had forced them off the road.

"Noel Strang, eh?" The chief frowned. "I've heard about him. Slick operator, but he's not on the 'Wanted' list right now. Do you know why your father is after him?"

"No, we don't," Frank said. "Dad just asked us to trail him and try to get a line on what he's up to."

"We got the license number," Joe added. "But we'd like to know if the man we were following was Strang. We didn't get a good look at him."

Collig jotted down the number. "I'll check it with the Motor Vehicle Bureau. I appreciate your stopping by."

The boys went outside to their convertible. As Frank felt in his pocket for the car keys, his expression changed to one of annoyance. "I've lost my pocketknife, Joe. Wonder if it dropped out back there when I was bending over that fellow?"

"Could be," Joe said. "We can search for it tomorrow. I want to take a look at that tiled square Chet told us about."

"Same here!"

Frank took the wheel and drove off through the late-evening traffic. Suddenly a red light flashed on their dashboard short-wave radio. Joe picked up the microphone.

"Joe Hardy here."

"Good evening, son." Fenton Hardy's voice came over the speaker.

"Dad! When did you get home?"

"Just arrived. Where are you fellows now?"

"We're downtown in the car. In fact, we're headed for home."

"Good. This case I'm working on looks pretty tough and I may need your help. I'll have to leave again first thing in the morning, so I'd like to fill you in on the details this evening."

"We'll be there pronto, Dad!"

A short time later the convertible pulled into the driveway of the Hardys' large, pleasant house on a tree-shaded street. The boys jumped out and hurried inside.

Fenton Hardy, a tall, rugged-looking man, was in the dining room having a cup of coffee. Seated at the table with him were Mrs. Hardy and the boys' Aunt Gertrude, his unmarried sister.

The detective greeted Frank and Joe with a warm smile. "Sit down, boys, and I'll tell you what this case is all about."

Mr. Hardy explained that he had been asked by a group of insurance underwriters to investigate a series of jewel thefts. The latest had occurred in New York the day before.

"We heard a news flash on that, Dad!" Joe exclaimed.

"Undoubtedly all the thefts have been pulled by the same gang," the detective went on. "And there's an odd feature. On every job, the guards or other persons involved seem to have lost their memory for a short period of time while the robbery was taking place."

"You mean they passed out?" Frank asked.

Fenton Hardy shrugged. "None of them recalls passing out. But they all report a sensation of coming to, or snapping out of a deep sleep, as if they had lapsed into unconsciousness without realizing it."

Gertrude Hardy, a tall, angular woman, pursed her lips and frowned shrewdly. "If you ask me, they were gassed," she declared. "Some kind of nerve gas, probably-squirted at the victims through a blowpipe."

Frank and Joe tried hard not to grin. Their aunt had definite opinions and never hesitated to express them.

"They may have been gassed," Mr. Hardy agreed. "But if so, it's strange that police experts were unable to discover any traces in the atmosphere afterward."

"Maybe the crooks sucked it all back into their blowpipes," Joe said mischievously.

Aunt Gertrude gave him a withering look.

"Making fun of me, are you? Well, maybe you have a better theory, young man!"

Laura Hardy, a slim and pretty woman, exchanged a fleeting smile with her husband. Both knew that Aunt Gertrude loved to talk about detective cases with her brother and the boys, even though she pretended to disapprove of such dangerous work.

"Matter of fact, we got gassed ourselves tonight," Frank put in quietly. He told about their chase of the black sports car, but glossed over the part about skidding across the road.

"Hmm." Fenton Hardy knit his brows. "Do you think the driver could have recognized you–maybe from seeing your pictures in the paper?"

Frank shook his head. "I doubt it, although he may have glimpsed us in his rear-view mirror when we passed a street light. I think that when he spotted a car tailing him, he used the smoke screen to shake us."

"Why, that man's a menace!" Aunt Gertrude blurted out indignantly. "Why didn't you radio the police at once? Mark my words, you'll–"

The ringing of the telephone interrupted Aunt Gertrude's prediction. Joe jumped up to answer it.

"Let me speak to Fenton Hardy," said a curt, muffled voice.

"Who's calling, please?" Joe asked.

"None of your business! Just tell him to get on the phone if he wants to learn something important!"

Fenton Hardy strode quickly to Joe's side and took the receiver. "All right, I'm listening."

"Another jewel heist has been planned. It's going to be pulled aboard a yacht named the Wanda. She's due in at East Hampton, Long Island, late tonight or early tomorrow morning. Got that?"

"I have it," the detective replied. "But who is this speaking?"

"A friend. And don't bother trying to trace the call!"

There was a cutoff click at the other end of the line. Mr. Hardy hung up thoughtfully and told the boys what the informer had said.

"I'd better follow up that tip-off," he added. "I'll drive down to East Hampton."

"Are you sure that's wise, Dad?" Frank asked worriedly. "The call may be a trick."

"It's a chance I'll have to take, son."

Mr. Hardy telephoned Suffolk County Police Headquarters on Long Island to report the tip. Before leaving the house, he suggested that the boys restudy the photo of Strang in his file, and also the typewritten data on the reverse side of it.

"Mind you, we have nothing on him," the detective said. "But I think he's one of the few jewel thieves in the country capable of masterminding a series of robberies like the ones I'm investigating."

"Do you want the police to take him in for questioning?" Joe asked.

"No, that would only put him on guard. But I would like to know what he's doing in Bayport!"

"We'll keep an eye out for him," Frank promised.

Mr. Hardy then placed a long-distance call to his top-flight operative, Sam Radley. Sam had flown to Florida with a charter pilot named Jack Wayne to wind up another case. Fenton Hardy instructed Sam to join him at East Hampton the following day.

Next morning, Frank and Joe ate a hearty breakfast of bacon, eggs, and homemade muffins, then started off in their convertible to pick up Chet Morton. After some grumbling, the stout boy agreed to help them search for the curious tiled square he had seen the night before. Frank pulled up on the dirt lane near the big oak tree.

"I don't know why I let you two talk me into this," Chet complained as they started up the slope. "I can't seem to stay out of danger when you're around."

Joe laughed. "Stop griping. You don't expect to hear any spooks in broad daylight, do you?"

When they reached level ground, Frank remarked, "Say, I see a house over there!"

Joe and Chet looked in the direction he was pointing. A large, weather-beaten mansion was visible through the trees some distance away,

"Didn't notice any lights over that way last night," Joe said. "Wonder if anyone lives there."

"Maybe not," Frank said. "Looks pretty run down."

For half an hour the boys searched among the tall weeds and overgrown shrubbery. They failed to sight the tiled surface Chet had described, or to find Frank's knife.

"Sure you weren't just seeing things last night?" Frank asked Chet.

Joe chuckled. "Maybe just hearing things, too?"

Before Chet could reply, a voice barked out, "Stand right where you are! Now turn around, all three of you!"

The boys whirled in surprise. A tall, hawk-faced man with a thin, prominent nose was standing among the trees watching them. He had one hand in his suit-coat pocket, as if concealing a gun.

Frank and Joe gasped. The man looked like the one in the photograph of Noel Strang their father had in his files!

CHAPTER III

The Purple Stone

"DON'T stand there gawking!" the man snarled. "What are you kids looking for?"

Chet gulped. "W-well-uh-you see, l-last night-"

"I lost my pocketknife," Frank spoke up. "We were trying to find it."

"Your pocketknife, eh?" The man scowled at the boys suspiciously. "You had no business nosing around here last night or anytime. This is private property. Now clear out!"

Chet, overcome with jitters, hastily started walking back to the car. Frank and Joe did not budge, and continued to stare at the man.

"You heard me!" he said in a loud, belligerent voice. "Beat it! And don't come back!"

He took a few steps toward the Hardys and crooked his arm as if he were about to jerk his gun hand out of his pocket. Without a word, the brothers turned and followed Chet.

"That is Noel Strang!" Joe whispered. "Think we should call his bluff?'"

Frank shook his head. "Not now. Remember what Dad said."

"He may not own this property," Joe argued. "If he does, maybe we can find out what he's doing here."

"I intend to," Frank said. "But let's try to do it undercover, without making him suspicious."

Chet had already climbed into the car. He was sitting stiffly in the back seat-still pale and nervous, but whistling off-key and trying to look casual.

Frank slid behind the wheel and Joe got in beside him. As they glanced back up the slope, the boys could see Strang watching them intently.

"Oh-oh," Joe muttered. "I just thought of something!"

"Like what?" Frank asked.

"If he's the one who used that smoke screen last night, he may recognize our convertible."

"Smoke screen!" Chet gasped. In the rear-view mirror, Frank could see that the fat boy's eyes were bulging with fear. "You mean that guy's a gangster?"

"Not exactly," Joe said, as Frank turned the car around. "Just a notorious jewel thief named Noel Strang."

Chet groaned as the Hardys told him the details. "Oh, this is great! I don't want to get mixed up in another one of your cases! You'd better take Joe home."

The Hardys grinned. "Chet, you know you eat up excitement as well as food," Frank said.

"It helps to keep your weight trimmed down," Joe suggested.

"Listen! I'll probably lose ten pounds just worrying about this thief," Chet retorted. "Strang may even send his men after us!"

Joe chuckled. "Just threaten to sit on 'em–that'll be enough of a scare."

Frank suddenly looked troubled. "Now I just thought of something, Joe."

"Bad?" Joe glanced at his brother.

"Not good. That knife has my name engraved on it. If Strang finds the knife, he may connect us with Fenton Hardy."

Joe gave a low whistle. "Let's hope he doesn't find it!"

A short time later Frank swung up the graveled driveway leading to the Mortons' farmhouse. Chet's pretty, dark-haired sister Iola was seated on the front porch with her blond, brown-eyed friend Callie Shaw.

Iola bounced up from the porch swing as the boys stepped from the car. "Hi!" she exclaimed. "Wait'll you see the surprise Callie and I have to show you!" The girls' eyes sparkled with excitement.

Joe grinned at Iola, whom he considered very attractive. "Sounds pretty important."

"Aw, it's probably some new doodads for their charm bracelets," Chet scoffed.

"Like fun!" Iola retorted. "It'll make you turn green with envy-I mean purple!"

As the boys followed the two girls into the house, Callie explained that she and Iola had been rock hunting the day before. With a giggle, she also whispered to Frank that Chet and Iola were rivals at rock hounding.

In the dining room, Iola went straight to the old-fashioned punch bowl on the buffet and took out a stone about the size of a grape. It was pale violet and roughly crystalline in form.

"Feast your eyes!" she said, waving the stone under Chet's nose.

"Well, hold it still so I can see it." The chubby youth stared in grudging admiration.

"It's beautiful," Frank said. "Is that an amethyst?"

Iola bobbed her head proudly. "A real one!"

"We took it to Filmer's Gemstone Shop this morning to make sure," Callie added. "Mr. Filmer identified it for us."

Chet's eyes bugged out in awe. "Wow! A real jewel!" he gasped. "Where'd you find it?"

Iola and Callie blushed with embarrassment. "We don't remember," Iola confessed.

"You don't remember?" Chet echoed. "How goofy can you get! Why, there might be a whole lode of amethysts around the spot!"

"But we picked up oodles of stones in several places," Callie explained. "The light wasn't good in the late afternoon and we didn't realize that this one might be valuable."

"We're not even sure which one of us found it," Iola put in. "We didn't get excited until we sorted the stones this morning."

Chet was about to make a wisecrack when Joe happened to glance out the window.

"Hey!" he yelled. "Your barn's on fire!"

The others stared and gasped. Black smoke was billowing out through the open barn door!

"Good grief!" Chet shouted. "And Dad's over at the vet's this morning! Quick! Get some fire extinguishers and buckets of water!"

The five teen-agers dashed outside, followed by Mrs. Morton, who had hurried upstairs from the cellar when she heard their cries.

There was no sign of open flames from the barn, so Frank and Chet plunged inside to get a pair of fire extinguishers hanging on the wall. Joe and the girls, meanwhile, prepared to form a bucket brigade from the pump.

"Oh, my goodness!" Mrs. Morton cried distractedly as she hovered outside the barn. "Shall I call the fire department?"

"Don't bother, Mom!" Chet shouted back. "This looks like a false alarm!"

Soon the smoke began to clear and the two boys emerged, grimy from the thick fumes. "A bucket of oil was burning," Frank explained, coughing.

"Sure beats me how it started," Chet added. "I wouldn't think heavy tractor oil could ignite by spontaneous combustion."

Relieved, they all trooped back to the house. Mrs. Morton provided soap and towels so Chet and Frank could wash in the kitchen. Joe and the girls returned to the dining room.

Iola went to pick up the amethyst but could not find it. "Callie, did you take our jewel outside with you?" she asked.

"No, you left it on the table, didn't you?"

"I thought I did." Iola hastily checked the punch bowl, then turned an anxious face to the others. "It's not here!"

A frantic search followed, with Joe scrabbling on the floor and the girls going through every drawer and compartment of the buffet. The amethyst was gone! Frank and Chet heard the news as they came into the dining room.

"Oh, fine!" Chet groaned. "First a fire, and now you girls lose the only valuable stone we've ever found!"

Frank and Joe looked at each other with the same thought in mind.

"I'll bet that fire was a trick to get us out of the house!" Joe exclaimed.

"You mean the stone was stolen?" Iola gasped.

"I'm afraid so," Frank said. "By the same person who set fire to that bucket of oil."

Callie's eyes glowed with a sudden recollection. "I heard a car start up down the road just as we came back to the housel" she said. "I'll bet that was the thief getting away!

Chet plumped himself down in a chair. "Boy, this is turning out to be one swell day." He grunted, then brightened. "Guess we may as well have lunch."

Frank telephoned a report of the theft to the police and then called home to notify his mother that he and Joe would be lunching at the Mortons'.

Aunt Gertrude took the message. "By the way," she said, "Tony Prito has called twice, trying to get hold of you and Joe. Wouldn't tell me what he wanted, but he did say it was urgent."

"Where can I call him?" Frank asked, "At his dad's office?"

"Mmm-no, I believe he said he was phoning from the boat dock."

"Okay, Aunty. Thanks."

Frank and Joe apologized to Mrs. Morton for hurrying through the hearty lunch she served them. As soon as they had finished, the brothers excused themselves to go and find Tony Prito.

Tony, a dark haired, good-looking boy, was a close pal of the Hardys and they often went out on Barmet Bay with him in his motorboat, the Napoli. Frank and Joe drove quickly to the boat basin but could not see Tony anywhere.

"I'll bet he's out in the Napoli," Joe said, staring out across the harbor.

"Probably so." Frank glanced up at the sunny sky and then at the gently white-capped blue waters of the bay. "Let's get the Sleuth, Joe, and try to find him."

"Suits me."

The Hardys hurried off to the boathouse where they kept their own motorboat.

At that moment Tony was just driving up to the Mortons' house in his father's pickup truck.

"Hi, Chet! Have you seen Frank and Joe today?" he called to the stout youth, who had come out to the porch.

"Sure. They had lunch here. Left about fifteen minutes ago, heading for the boat dock to find you."

Tony suddenly went pale. "Man, I hope they don't go out in the Sleuth!"

"Why not?" Chet asked, puzzled.

"Hop in and I'll tell you. We'd better get there fast!"

Chet hardly had time to get into the cab before Tony threw the truck into reverse and backed up. As he swung the vehicle around and sped down the road, he explained, "I saw two tough-looking guys sneak out of Frank and Joe's boathouse. Somehow I have a hunch those men were up to no good!"

"Did you recognize them?" Chet asked, wide-eyed.

"No, but I'm afraid those men may have sabotaged it!"

"Didn't you warn Mrs. Hardy and Aunt Gertrude?"

"Guess I should have," Tony said ruefully. "But I didn't want to alarm them."

As the truck pulled up on the quay, Chet exclaimed and pointed toward the water. "There they go now!"

The Sleuth, with two figures aboard, was put-putting out across the bay.

"We're too late," Tony groaned.

The boys leaped out of the truck and began shouting and waving frantically to their friends. But the Hardys' boat was too far out for the brothers to hear the cries.

Suddenly a loud explosion shook the Sleuth!

CHAPTER IV

The Jigsaw Face

THE force of the blast jerked the bow of the Sleuth up out of the water! Both its occupants were hurled overboard and the boat itself overturned. Smoke billowed from the scene.

"Come on!" Tony cried to Chet. "We must get out there and pick them up!"

"Where's the Napoli?" Chet puffed as they ran along the quay.

"I left it tied up at the North Dock."

People were already gathering excitedly along the waterfront. The two boys reached the North Dock and leaped into the motorboat. Chet cast off and Tony gunned the outboard into life. In a moment they were speeding out on the bay.

Chet, who was seated in the bow, shouted in relief, "Looks as if Frank and Joe are okay!"

The Hardys had been struggling in the water, but could now be seen clinging to their overturned craft. The Napoli came alongside.

"Boy, this is what I call service!" Joe said as he and Frank were hauled aboard.

Tony explained, "We came to give you a warning."

"Tony, we came out here looking for you" Joe replied. "Your boat wasn't in the basin."

"No, I took it out this morning and tied up at the North Dock when I came back."

"What did you mean about warning us?" Frank put in.

Tony hastily told about seeing the two men sneak out of the boathouse. Just as he finished, a Coast Guard rescue launch reached the scene. Other boats were approaching also.

"Everybody okay?" the chief petty officer called out from the Coast Guard launch.

"They're okay but plenty wet," Chet replied.

"What happened?" the officer asked.

"Some kind of explosion in the forward compartment," Frank told him. "We suspect sabotage."

The chief ordered his coxsin to maneuver the launch closer to the overturned craft. A hole had been blown in the hull near the bow, but the boat's special flotation apparatus in the forward space had kept it from sinking.

"Can your friends tow the boat to a repair dock all right?" the chief asked the Hardys.

"We can manage, if someone will give us a hand," Tony spoke up.

"I'll help you, lads!" called a man from a nearby motor cruiser.

"In that case, I'd like you fellows to come back to the Coast Guard station with me and make a report," the officer told Frank and Joe.

The Hardys transferred to the Coast Guard launch, which immediately sped off to its base. Meanwhile, Tony and Chet tackled the job of putting a towline onto the Sleuth, with the help of the man in the motor cruiser.

At the Coast Guard station Frank and Joe told their story to a lieutenant named Anson. "You're Fenton Hardy's sons, aren't you?" he asked.

"Yes, sir," Joe answered.

"Is this sabotage connected with one of his cases?"

Frank hesitated. "We think so, sir, but we don't know yet."

Lieutenant Anson asked, "Any theories?"

"Someone was trying to kill us, or at least scare us off our investigation," Frank said. "My guess is the bomb was detonated chemically in some way by the Salt water. But I have a hunch it went off too soon–the saboteurs hoped we'd be farther out in the bay."

"Right," Joe agreed. "I'll bet the blast was supposed to swamp the boat fast, drown us, and send all our evidence against them to the bottom. But luckily for us, the boat overturned and stayed afloat, giving us something to cling to–"

Lieutenant Anson took down their statements, then said, "For the record, I'll say you're carrying out your own investigation. But please keep us informed."

He had an enlisted man drive the boys back to their car. Frank and Joe went home, where Aunt Gertrude greeted them with clucks of disapproval.

"Well, I never! It's a good thing your mother has gone to the library board meeting!" Miss Hardy ordered the boys to take off their soaked shoes to avoid tracking up the carpet, then went on anxiously, "What happened? Did that crook you're after make you walk the plank?"

Frank chuckled and gave her a damp hug, which Miss Hardy tried to fend off. "Slight accident, Aunty–a dunking we didn't expect."

The boys had just changed into dry clothes when the telephone rang. Joe answered. The caller was Chief Collig.

"Got a report from the Motor Vehicle Bureau on that sports-car license number," he said. "It's registered in the name of Aden Darrow."

"Never heard of him," Joe replied.

"Nothing on him in our files, either."

"What about the address?"

"A street number in Eastern City," Collig said. "I checked with the police there but they couldn't help. The whole street's been demolished for an expressway."

"Dead-end clue. Well, thanks a lot, Chief."

A short time later Tony Prito and Chet arrived. They reported that the Sleuth had been safely towed to the repair dock. Frank telephoned to determine the cost of repairing the boat, then the boys gathered to discuss the day's events. Frank and Joe quickly told Tony about the case.

"You figure the men who planted the bomb were working for Strang?" Tony asked.

"Could be," Frank said. "Especially if he found my knife and learned our name."

"I'll bet he recognized us last night!" Joe put in.

"How about that sneak who took Iola and Callie's amethyst?" Chet asked. "Maybe Strang did that too. You said he's a jewel thief."

Frank frowned. "That's true. But he's a big-time operator. I doubt if the amethyst's worth enough to tempt him."

"Anyhow, Strang's definitely got business in this area," Joe said. "Do you think he could be hiding out at that old house-the one we saw him near this morning?"

"Could be," Frank said.

Tony asked where the place was located. When Joe told him, Miss Hardy exclaimed, "Why, that's the old Perth mansion!"

"Do you know who lives there?" Frank asked.

"No one, far as I've heard," she replied. "Hasn't been occupied for years. The place had what you might call a sinister reputation."

"How come?" Joe inquired.

"Seems someone died there under mysterious circumstances. Don't recollect just who. But there was talk about the place being haunted."

"Haunted?" Chet swallowed and turned pale.

Miss Hardy sniffed. "All stuff and nonsense. Some folks will believe anything. That was years ago-even before you boys were born."

"Tell us some more, Aunty," Frank urged.

Gertrude Hardy settled into her favorite chair. "Well, the house originally belonged to a man named Jerome Perth. Not a nice person at all, from what folks used to say."

"Who was he?" Frank asked.

"Some sort of big business tycoon-but a shady operator. People accused him of all sorts of things-stock swindles, patent infringements. I don't know what all. But I guess no one ever pinned anything on him,"

"Must have been pretty slick," Tony remarked.

"Oh, he was," Miss Hardy agreed. "And he made a lot of enemies-in fact, some of the people he'd cheated even tried to kill him. Finally he retired to that mansion he built and lived there in fear of his life."

"So his swindles didn't bring him any happiness," Joe remarked.

"No, indeed. I recall hearing he had his study on the ground floor fitted up with a bed and hardly ever stirred out of that one room."

"But you still don't remember who died there under mysterious circumstances?" Joe said.

Aunt Gertrude shook her head. "Some relative, I think. But I don't recall the details."

Frank, meanwhile, had a sudden hunch. He telephoned Iola Morton to ask if anyone else had been in the gemstone shop when the girls showed the proprietor their amethyst.

"Why, yes, there was," Iola replied. "Another customer came in right after we did. I remember he asked us where we had found our stone." Suddenly Iola gasped. "Oh! You mean maybe he was the one who stole our amethyst?"

"Could be," Frank said. "He might have shadowed you back to your house. Is Callie still there with you?"

"Sure. Want to talk to her?"

"We'll come out."

Five minutes later Frank, Joe, and Chet were on their way to the farm in the Hardys' convertible. Tony had to go back to work at his father's construction company.

When the boys arrived at the Mortons' house, Frank carried in his father's facial identification kit. Besides an illuminated viewing screen, the kit contained strips of film showing hundreds of different hairlines, eyes, ears, noses, chins, eyeglasses, and hats.

Iola and Callie were fascinated as the Hardys began asking them to describe and identify the features of the stranger at the gem shop.

"It's like putting together a jigsaw puzzle!" Callie exclaimed.

Bit by bit, the film strips showing the man's features were laid together over the viewing screen until a whole face had been assembled.

"For Pete's sake!" Joe exclaimed. He and Frank stared at each other. "That's the guy we picked up unconscious last night!"

Chet peered over their shoulders, open-mouthed with surprise. "It is for a fact!"

"Joe," Frank said, "suppose you take that face to the gem shop and ask Mr. Filmer if he knows the man."

"Okay. How about you?"

"I want to go to the Bayport Times office and see if I can dig up any stories on the Perth mansion from their back files."

Joe dropped his brother off at the newspaper office and a few minutes later pulled up in front of Filmer's Gemstone Shop. He carried the kit inside and spoke to the proprietor.

Mr. Filmer, a skinny man with thick bifocal eyeglasses, seemed oddly nervous. "I-uh-r-really don't recall anyone else being in the shop when Iola and Callie were here," he stammered.

"Please try to remember," Joe begged.

"I'm afraid I can't."

"All right. At least let me show you a picture of the man's face and see if you–" Suddenly Joe broke off. The door to the back room was ajar and he had just seen it move slightly.

Someone was eavesdropping behind the door!

"So that's why Filmer won't help me!" Joe thought. "I'll bet he's afraid of the person hiding back there!"

The young detective wondered what to do. If he asked Mr. Filmer's permission to look into the back room, it would forewarn the eavesdropper. But if he acted on impulse–Joe darted behind the counter and yanked open the door.

A tall, sandy-haired man, who looked like the one in the picture, streaked across the back room toward a window! Joe rushed forward and lunged at him. The stranger grabbed a stool and hurled it at Joe.

The stool struck Joe on the temple and he sank to the floor unconscious!

CHAPTER V

Spook Hound

As JOE regained consciousness, he felt something cold and damp on his forehead. He was propped in a corner of the gem shop's back room and Mr. Filmer was bending over him, applying a wet towel to the bruise.

"Feel all right?" Mr. Filmer asked anxiously.

"I–I guess so, except for a sore head."

"Dear me! You have quite a lump there!"

"Never mind that." Joe struggled to his feet. "What about that guy who slugged me with a stool?"

Mr. Filmer pointed helplessly to an open window. "He got away and ran off down the alley."

"I suppose he's the one who was here when Iola and Callie brought in their amethyst?" Joe said, repressing an angry comment.

Mr. Filmer reddened. "I'm terribly sorry I had to lie to you. He was hiding back here all the time, listening. I was too frightened to talk."

"Well, he's not here now-so who is he?"

"I really don't know," Mr. Filmer said, looking bewildered. "He often drops into the shop to talk to the local rock hounds, and always seems especially interested in amethysts. That's about all I can tell you."

"When did he get here?" Joe asked.

"Just a few minutes before you did. He asked me if anyone had been inquiring about him. When I said No, he warned me to keep my mouth shut or else he'd have me beaten up. Then he saw you coming and ducked into the back room."

"If he ever shows up again," Joe said, "will you try to notify the police right away?"

"I certainly will!" Mr. Filmer nodded vigorously, eager to make amends.

Joe thought of trying to lift some fingerprints, but he remembered that the man had been wearing gloves. Before leaving, Joe telephoned a report of the incident to Chief Collig.

When Joe reached home, his mother insisted upon applying a soothing dressing to his swollen temple. Aunt Gertrude hovered close by, supervising the treatment and muttering darkly about the dangers of detective work. Joe merely grinned at her sharp comments.

Soon afterward, Frank arrived home. He took one look at Joe, who was curled in an easy chair watching TV, then let out a whistle.

"Where'd you get that decoration?"

"I connected with a stool," Joe said wryly. He told Frank what had happened at the gem shop and added, "I still can't figure how that man knew we'd go there to check on him."

"Probably followed the same line of reasoning we did," Frank replied. "The girls just picked up the amethyst yesterday-so the shop is the only place where an outsider could have learned about their find. Besides, he had quizzed Iola and Callie about the stone, and you say Filmer knew of his interest in amethysts."

"In other words, he guessed we might put two and two together. Rather than take any chances, he decided to bulldoze Filmer into silence."

Frank nodded, and Joe added, "Now how about telling me what you found out."

"I got the full story," Frank said eagerly. "The person who died at the Perth mansion under mysterious circumstances was Old Man Perth's nephew. Must have been quite sensational. The Times had a flock of old write-ups on it."

Joe's eyes brightened with interest. "What happened?"

"Well, the nephew–Clarence Perth–moved into the mansion after Jerome Perth passed away from a heart attack. He took over the old man's bedroom-study. But he lived only a few days to enjoy his inheritance."

"How come?"

"One night, long after midnight, the servants heard him scream in terror," Frank continued. "They broke into the room and found him lying on the floor with his skull fractured. And get this–just before he died, the nephew muttered something which sounded like 'the floor'!"

Joe gave a whistle. "Wow! When Chet hears that, he'll be positive it was a ghost that screamed at us last night."

"There's more," Frank went on. "Both the door and the windows of the room had been locked from the inside and none of them broken-so there was no way a killer could have entered the room or escaped."

"How about trap doors or trick wall panels?"

Frank shrugged. "The stories said the police looked for secret exits but didn't find any. Of course, criminal-detection methods then weren't what they are today."

"What about the ghost angle?" Joe queried.

"There are several follow-up news items. They said that a number of persons had reported seeing a ghostly figure prowling about the Perth estate."

"Humph! No doubt there'll always be gullible simpletons!" said a peppery voice. Aunt Gertrude planted herself in an easy chair and began darning socks. "Don't mind me." She sniffed. "Just go right on with your wild talk."

Frank and Joe exchanged grins, knowing their aunt was eager to hear more. She looked gratified when Frank repeated the information he had gleaned from the Bayport Times.

"Yes, I remember now about Perth's nephew," Miss Hardy said reminiscently. "Poor fellow! Almost seemed as if Fate had marked him out to pay for his uncle's misdeeds."

At dinner Frank and Joe were silent and thoughtful. Neither believed that the weird screams they had heard near the Perth mansion could have been made by the nephew's ghost. Nevertheless, it was an eerie notion!

"I'd like to go back to that mansion," Joe said as the family finished dessert. "I have a hunch we'll find some answers there-about the ghost and Strang too."

Frank agreed. "We'll go as soon as it's dark."

Two hours later the brothers climbed into their convertible and headed toward the outskirts of Bayport. Their tires hummed in the still, moonlit night air and wispy clouds covered the sky. When they turned onto the dirt lane, Frank switched off their headlights and soon afterward pulled in close to a screen of shrubbery.

"Better take our flashlights," Joe murmured.

The boys got out and headed up the slope. In the distance they could see a few gleams of light from the house.

"Someone's in the haunted house!" Joe remarked. "Maybe Strang. We'd better watch our step!"

The Hardys threaded their way among the trees and underbrush. Suddenly a ferocious snarl made them whirl to the left.

A huge, savage-looking hound stood facing them, its eyes glowing in the dark like coals of fire! Again it snarled, and seemed about to spring at the two intruders!

"Come on! Don't argue with it!" Frank muttered. He started to back away hastily, but Joe clutched his arm.

"Wait, Frank! That thing's not alive-it's just a mechanical dummy!"

Incredulous, Frank did a double-take. Then he realized that Joe was right. "Well, I'll be a moldy dog biscuit!" he gasped. "That hound sure looks real enough to bite your head off!"

"We must have crossed an invisible beam that made it light up and snarl," Joe surmised. He reached out a hand to touch the device, as if to reassure himself that the "dog" was not flesh and blood.

"Hold it, Joe!" Frank jerked his brother's hand away. "That thing looks like metal-it may be electrically charged."

Stripping off his belt, Frank held the leather belt and swung the buckle lightly against the mechanical hound. A hissing blue-white spark illuminated the darkness as metal touched metal!

"Wow!" Joe gasped. "That really would have given me a jolt! Say, Frank, do you suppose the guy we found here could have been shocked unconscious by some electrified gadget?"

"Sounds like a good guess. And that gives us another reason for watching our step."

More cautiously than ever, the Hardys approached the old mansion. The house, covered with fading clapboards, was fronted by a low veranda and topped off with turrets and decaying latticework. Ragged clumps of shrubbery grew close to the walls.

"Let's try those lighted windows on the first floor," Frank suggested.

The boys crept close enough to peer inside. Bookshelves, a desk, chairs, a bureau, and a bed lined the walls of the room.

"This must have been Jerome Perth's bedroom-study," Joe whispered.

He brought his face up closer to the pane for a better view, then gave a cry of astonishment. "Frank, look! The room has no floor!"

CHAPTER VI

Symbol in Brass

FOR a moment Frank thought his brother must be joking. Then he, too, put his face to the window-pane. Beneath the room's furniture he could see only gaping darkness!

"This is crazy!" Frank muttered. "That furniture can't just stand in mid-air!"

"If only we could see better," Joe said, flattening his nose against the glass in an effort to peer downward. Suddenly Frank gave a warning hiss and yanked Joe into a crouched position.

"What's wrong?" Joe whispered.

Frank pointed off beyond the rear of the house, In the distance a tiny light could be seen moving among the trees. The boys shrank back into the shadows of some shrubbery.

As they waited, Joe's eyes fell on what looked like an old coin. It was lying on the ground in the patch of light outside the window. Joe reached out and pocketed it.

Meanwhile, the oncoming beam was zigzagging slowly about the grounds. Minutes went by. A night breeze sighed eerily among the hemlocks and cypresses. Bit by bit, the light moved closer to the boys' hiding place.

Frank strained his eyes in the darkness. Suddenly his scalp prickled. "Joe!" he gasped. "Do you see what I do?"

"I sure do!" Joe gulped.

The light was being carried by a ghostly white-robed figure! But common sense told the boys the figure must be human.

"This is our chance to lay that spook story to rest once and for all," Frank whispered.

Joe glanced at his brother. "You mean we rush the ghost?"

"Right–but not yet. Wait till I give the word."

The white figure flitted along, pausing every so often amidst the tall underbrush. For a time it seemed to be approaching the house. Then the light moved off in another direction.

Frank put his mouth close to Joe's ear. "Let's sneak up and take Mr. Spook by surprise now!"

Silent as shadows, the Hardys darted out from the shrubbery. Moving with swift steps, they closed in toward the phantom figure. But Joe, overeager, caught his foot in a tangle of underbrush and thudded to the ground.

The "ghost" whirled, evidently startled by the noise. The flashlight it was carrying raked the two boys, then winked out abruptly. An instant later the figure had slipped away into the darkness!

Frank halted only long enough to make sure his brother was unhurt, then raced in pursuit. Joe scrambled to his feet.

By now the white-robed figure was nowhere to be seen. Then Joe suddenly glimpsed something pale among the trees. Was the spook trying to evade them by doubling back toward the house? Joe sprinted to intercept it.

He saw the phantom figure pass between two trees. Instantly the faint ringing of an alarm bell could be heard from inside the mansion!

"There must be another electronic-eye beam between those trees!" Joe realized.

Floodlights blazed on around the house. The front door burst open and three men dashed outside. The ghost, meanwhile, had veered to the left and was disappearing into the darkness again-this time toward the road, but away from the Hardys' car.

Joe halted, uncertain what to do next. If he continued the pursuit, he would risk being cut off by the men from the house before he could get back to the convertible.

"For all I know, they may be the ones who blew up our boat!" he said to himself.

As the men came closer, Joe made a fast decision and darted off among the trees. A moment later he was startled by a rustle of shrubbery close by. A shadowy figure was running alongside him! "You okay, Joe?"

"Yes. But wow! Don't give me heart failure like that!"

The sounds of pursuit grew fainter and presently the two boys reached sloping ground and headed toward their car.

Both boys hopped into the convertible. Frank keyed the starter and the engine came alive with a roar. Spinning the wheel, he sent the car zooming down the lane. "Talk about fast getaways-!" Joe panted as they reached the highway.

"Did you get a look at those men from the house?" Frank asked.

"Not too good a look, but I think one of them may have been Noel Strang."

As the brothers came in the kitchen door of the Hardy home, they heard a loud buzz from the basement.

"The short-wave radio signal!" Frank exclaimed. He and Joe hurried downstairs and switched on the powerful set which the Hardys used for secret communications.

"Fenton H. calling Bayport. Come in, please." The last words swelled to stronger volume as Joe tuned the receiver.

"Bayport to Fenton," Frank said. "We read you loud and clear!"

"Good! I hoped I'd catch you boys in."

"How'd that telephone tip pan out?" Frank inquired eagerly.

"It hasn't so far," Mr. Hardy reported. "The Wanda didn't arrive until six this evening. Its passengers are all wealthy people, and there's a fair amount of jewelry aboard. But as yet we haven't turned up a single clue that might indicate a robbery is planned."

"Do you think the tip was phony?"

"Too early to tell yet. The police have a dragnet out but they haven't spotted any likely suspects. Of course it's possible the jewel thieves called off the job for some reason."

"Dad, it's also possible the gang wants you stymied there in East Hampton while they prepare to pull a job somewhere else," Frank pointed out.

"That's what I'm afraid of," Mr. Hardy agreed. "Meanwhile, Sam and I can't do much. What's the picture there in Bayport?"

Frank rapidly briefed his father on the day's developments. Mr. Hardy was stunned to hear about the bombing of the Sleuth and the attack on Joe at Filmer's Gemstone Shop. Also, he was intrigued by the Motor Vehicle Bureau's report.

"I'm sure I've heard that name, Aden Darrow, but I can't place it," the detective said, "Try checking my criminal file."

After a hasty conference with his operative, Sam Radley, Mr. Hardy added, "Son, the way things are popping there in Bayport, I think Sam had better fly back and help you boys with your investigation. I'll get hold of Jack Wayne. He should be able to land Sam there by midnight."

"Okay, Dad. We'll meet Sam at the airport."

After signing off, Frank and Joe hurried upstairs to their father's study. A thorough check of his file revealed no criminal listed under the name of Darrow.

"Dad must've been mistaken," Joe concluded.

Mrs. Hardy and Aunt Gertrude were watching a movie on television. The brothers joined them.