The Disappearing Floor Read online

  “Sure glad you boys are safe,” he murmured.

  “Glad we’re safe!” Joe echoed. He flashed his brother a puzzled glance.

  “Must have something to do with the cabin,” Frank said. “You were trying to warn us—is that it, Jack?”

  Their friend gave a faint nod. “I was waiting there with that other guy ... to meet the boss. Then he ... he got word by radio that you two might show up. Radio message said to booby-trap the cabin w-with explosive ... and pull out.”

  “Wait, let’s get this straight,” Frank put in hastily. “You flew here because Hirff offered you a chance to join the gang?”

  Again the pilot nodded.

  “And your plane was hidden in the brash so no one would spot it?” Joe added.

  “Th-that’s right,” Jack mumbled. “We were just about to leave when your boat pulled in. Barney, he’s the guy who was with me ... he said we should lie low till you were out of sight ... then take off ...”

  Jack’s voice was getting weaker. Frank urged him not to talk, but the pilot, now lapsing back into unconsciousness, seemed not to hear.

  “B-Barney was holding a gun on me ... test ing me to s-see what I’d do. Only way I could warn you was to—”

  Suddenly Jack’s head lolled to one side.

  “He’s passed out again, poor guy,” Frank said, checking the pilot’s pulse.

  “He saved our lives, Frank,” Joe murmured. “With that cabin deserted, we’d have walked inside and been blown sky-high if Jack hadn’t—”

  The wilderness quiet was suddenly shattered by the staccato noise of a boat engine. The Hardys leaped to their feet and saw their own motorboat shoot out from the creek! Aboard was the man who had been hurled clear of the plane—the man whom Jack had called Barney.

  “What a couple of nitwits we are!” Joe burst out furiously. “While we were talking here, we let him circle through the woods and grab our boat!”

  There was no possible chance of retrieving the craft. It was already picking up speed—heading out of the bight toward the open sea.

  “The prize boner of all time!” Frank groaned. “We’re stranded here, Joe! And Jack needs medi cal attention!”

  The photographic print of the map was in the boat, and neither boy could remember any inland details, but Joe felt sure the nearest road was at least ten miles away.

  “Looks as though we have two choices, Joe,” Frank said thoughtfully. “We can wait here till the folks back in Bayport get worried and come looking for us. Or one of us can try to find a road and flag down a car for help.”

  Joe shook his head. “Pretty long shot. Whoever went might not be able to find his way through the woods before dark. But there’s one other possibility, Frank.”

  “Such as?”

  “Try to get into the cabin without exploding the booby trap and use the gang’s radio.”

  “You’re right! I never thought of that.” Frank rubbed his jaw worriedly and considered.

  The boys’ debate was cut short as they saw a small cruiser heading into the bight. Frank and Joe jumped up and down, yelling and wigwagging their arms, but they soon realized the signals were unnecessary. The cruiser evidently had been attracted to the scene by the smoke and flame of the burning airplane.

  The skipper of the cruiser brought his craft in close to the boys and shouted through cupped hands, “What happened? Do you need help?”

  “We sure do!” Frank yelled back. “A plane crashed and the pilot’s injured! We’re stranded here! Can you get us to Bayport?”

  “You bet I will!” the skipper replied heartily.

  Normally the Hardys would not have risked moving a man in Jack’s condition. But they felt they had no choice. Using a tarpaulin from the cruiser as a makeshift stretcher, they carried him through the shallow water and loaded him gently aboard the boat.

  Mr. Webb, the elderly, white-haired owner of the cruiser, revved his engine and they started out of the bight.

  “Too bad I have no radio, boys, or we could call ahead and have an ambulance waiting.”

  “We’re mighty grateful, anyhow, sir,” Frank replied. “If you hadn’t come along, I don’t know what we would have done.”

  There seemed little chance of sighting or overtaking the stolen motorboat. But as they approached the bay, Joe thought he glimpsed the craft and asked to borrow Mr. Webb’s binoculars.

  “That’s our boy, all right!” he said a moment later, passing the glasses to Frank. “He’s heading somewhere near Sea Gull Cove!”

  Minutes after they docked, an ambulance came screeching to the scene in response to a phone call by Frank. An intern gave Jack emergency treatment. Then the injured pilot was transferred from the boat on a stretcher. The Hardys followed in their convertible as the ambulance sped off, siren wailing.

  From the hospital, Frank telephoned Police Chief Collig and made a full report. The chief promised to have state troopers dispatched at once to the cabin to disarm the booby trap and search for clues. He also promised an immediate search for the stolen boat.

  “Incidentally, Frank,” Collig went on, “Tiffman, the messenger, and the watchman were all given lie-detector tests this afternoon.”

  “How’d they make out?” Frank asked.

  “Believe it or not, all three are in the clear.” Collig sounded thoroughly irritated and baffled. “I don’t know what kind of trick was played, but I’ll get to the bottom of this yet!”

  After hanging up, Frank called the boat livery and explained what had happened. “I’m sure the police will recover it,” he added.

  A few minutes later a doctor stepped out of the emergency ward. “Your friend seems to be in fair shape—no broken bones,” he told the boys. “However, he’s still unconscious and may have a concussion.” The Hardys felt relieved that the news was no worse.

  It was now past six o’clock, and the boys were due home for dinner. But Frank had an idea which he urgently wanted to check out with Mike, the night watchman at the Haley Building. He telephoned home, then the brothers drove from the hospital.

  “What can I do for you, boys?” Mike greeted them. “Still huntin’ clues to what happened here last night?”

  “Well, sort of,” Frank said. “I’d like to ask you some questions and find out exactly what took place before and after the messenger came.”

  “Okay, shoot!”

  Probing insistently, Frank had the watchman go over everything that had happened the night before. It turned out that Mike’s recollection was hazy for two periods of about twenty minutes each—one around seven o’clock and the other around eight-forty-five.

  “Guess I must’ve dozed off,” the watchman admitted a bit shamefacedly. “I remember comin’ to with a start both times.”

  As the boys left the building and got into their car, Joe remarked, “So he blacked out twice! That sounds like the same method used on all the other jewel robberies!”

  “Which backs up Dad’s hunch.” Frank’s voice was tense. “Joe, I think I can explain the mystery of what happened here last night!”

  CHAPTER XVI

  Riddle With Three Answers

  JOE glanced eagerly at his brother as their convertible pulled away from the curb. “Let’s hear your theory, Frank!”

  “Chief Collig says the lie-detector tests show that all three people involved are telling the truth,” Frank began. “The watchman, the messenger, and Mr. Tiffman.”

  “So?”

  “Therefore,” Frank continued, “we can assume the watchman did take the messenger up in the elevator—but not to the fifth floor. And O’Bannion did deliver the gems—but not to Tiffman’s office.”

  “Now wait a minute,” Joe said. “If O’Bannion didn’t take the diamonds to Tiffman’s office, where did he take them?”

  “To an office on the sixth floor—or possibly the fourth.”

  “How do you figure that?”

  “The watchman blacked out twice,” Frank replied. “During that time, someone could have tamper
ed with the elevator controls and also with the office numbers.”

  Joe frowned. “So Mike thought he was letting the messenger off on five. But actually it was one floor higher or lower.”

  “Right ”

  “Could the elevator setup actually be doctored to fool the operator that way?” Joe asked.

  Frank nodded as he braked for a red light. “I’m sure it could, Joe. That elevator is a push-button job with solid doors—not an old-fashioned cage with manual control. A smart mechanic could make the elevator stop at the wrong floor just by switching a few wires beforehand—and the person inside wouldn’t know the difference-even the watchman himself—unless he timed the ride.”

  “How about when the messenger rang to go down?” Joe asked.

  “That makes a light flash on the control panel,” Frank replied. “But let’s say the wiring had been tampered with. O‘Bannion rings from Six, but the light shows Five. Mike pushes the button for Five—but the elevator actually goes up to Six, where O’Bannion is waiting. Neither one realizes anything is wrong.”

  “Wow! Pretty slick!” Joe exclaimed. “And the office numbers were switched too, eh?”

  “Yes—probably by a confederate, to speed up the job. The doors aren’t glassed, with the numbers and names painted on them. They have metal numerals and name plates screwed on.”

  “Which would be easy to change,” Joe agreed. “The crooks could have had duplicate name plates made up beforehand to match the ones on Five.”

  “And they wouldn’t have needed to substitute all of them,” Frank added as he swung off Main Street into the residential area of Bayport. “Just on the doors the messenger would see. And, of course, substitute fives for the sixes.”

  “Sounds foolproof,” Joe said. “One of the crooks waits in the phony office and takes the gems. Then after the messenger leaves, they black out the watchman again and switch everything back the way it was before.”

  “Right,” Frank replied. “Now the question is—how do the crooks do their blackout trick?”

  “I’ve been thinking about that,” Joe brooded. “Frank, that may be where Professor Darrow and his scientific know-how come into the picture.”

  “You mean he’s in cahoots with Strang?”

  “Maybe.” Joe shrugged. “Perhaps he’s even trying to work off a grudge against society because no one would back his research, or he may have been brainwashed.”

  “Could be,” Frank agreed. “He sounded a bit odd from what Dean Gibbs told us.”

  Frank swung into the Hardys’ drive. “Another thing, Joe—what did that remark you heard on the tunnel phone mean?”

  “About the ‘disappearing floor’? I have a hunch it referred to the Haley Building job.”

  “That’s one possibility. Actually, there are three ‘disappearing floors.’ One—that phonily numbered floor at the Haley Building. Two—the hinged tiled summerhouse floor. And three—that invisible floor of Old Man Perth’s bedroom-study at the mansion.”

  Joe chuckled. “A riddle with three answers!”

  Aunt Gertrude suddenly thrust her head out the side door. “Are you expecting dinner to be served in the car? Food’s cold already!”

  “Sorry, Aunty,” Frank said. “It’s my fault.”

  Miss Hardy was curious about the latest developments in the case. At the table she listened eagerly as the boys told about the startling events at Tigers’ Bight. Both she and Mrs. Hardy expressed concern over Jack Wayne.

  “Oh, I hope there won’t be any aftereffects,” said the boys’ mother.

  Before the brothers could be served dessert, Tony and Chet arrived with more exciting news.

  “We found a cruiser called the Seacat!” Tony announced breathlessly. “It looks like the one we saw before that frogman attacked Joe!”

  “Where is it now?” Frank asked.

  “In one of those coves just off Shore Road,” Chet blurted out.

  Aunt Gertrude sputtered indignantly as Frank and Joe hurried away without waiting for any pie à la mode. They jumped into their convertible and followed Chet’s jalopy.

  Dusk was falling as the four friends pulled up near the cove. An old, rather battered-looking coupé was parked among the trees.

  “Must belong to someone on the cruiser,” Tony speculated. “There’s nothing else around here.”

  “I have an idea,” Joe said. “Let me take the convertible, Frank. Chet, you park in that next grove, and I’ll meet you fellows in a few minutes down in that clump of willows on the cove.”

  The others agreed, wondering what he had in mind. After Joe had made a U-turn and driven off, Chet parked his own car, then started down the hillside toward the cove with Frank and Tony.

  The three boys hid among the willows and looked out across the water. The cruiser lay silently at anchor amid the deepening twilight, with a dinghy tied alongside. A faint, wavering light came through the cabin portholes.

  Ten minutes went by. At last Joe joined them.

  “I borrowed Dad’s radio signal-sender,” he explained, “and attached it to the axle of that coupé so we can trail it.”

  “Smart idea,” Frank said approvingly.

  A few more minutes passed. Then the light aboard the cruiser went out. Presently a shadowy figure emerged from the cabin, but it was now too dark for the boys to make out the man’s features. He glanced around furtively, then climbed into the dinghy and began rowing ashore.

  “He sure acted sneaky,” Tony whispered.

  “He’s probably not the owner,” Frank surmised. “I’ll bet he had no right to be aboard.”

  The man rowed across the cove, moored the dinghy to a tree, and started up the hillside.

  “He must be the person who parked that coupe,” Joe muttered excitedly.

  The boys hurried back to their own cars. Joe had parked in the grove, close to Chet’s jalopy. Almost instantly they heard the coupé start up, and a moment later it drove past. Joe switched on the special receiver for the radio-tailing device. A low, steady whirring wail issued from the speaker.

  “Okay, let’s go!” he told Frank.

  The convertible swung out onto the road. Chet’s jalopy followed. Frank kept his headlights dimmed and stayed a safe distance behind the coupe. It circled Bayport and turned onto the road the black sports car had taken three nights earlier. Joe traced the coupé’s course by manipulating a loop antenna.

  “He’s going to the Perth mansion!” Joe exclaimed as a sudden fade in the radio howl announced a turn by their quarry.

  The boys pulled off the road and waited a few minutes so as not to betray themselves. Then they, too, entered the dirt lane. After parking in some shrubbery, they began searching for the coupe. Frank soon spotted it standing half-hidden among some trees farther down the lane.

  “Looks as though he’s trying to stay undercover himself,” Tony muttered.

  “I’m sure he’s not one of Strang’s men,” Frank agreed as Joe jotted down the license.

  “How are we going to find him?” Chet asked.

  “Scout around and use our eyes,” Joe replied.

  The four boys started up the slope. They all swung around with a start as a bloodthirsty snarl sent their pulse rates skyrocketing. Frank had to clamp a hand over Chet’s mouth to prevent the stout youth from shrieking.

  “Steady, pal! That’s just a mechanical spook hound—to scare off people like us.”

  Chet gulped as the fiery-eyed hound snarled again.

  “It just succeeded with one person!” the fat boy announced and started back down the slope. Frank calmed him and they went on. Tony and Chet waited in the shadows as Frank and Joe made their way to the house. They had just reached the porch when they heard a muffled “Ssst!” from Tony and turned.

  A white phantom was moving toward the house.

  “The galloping ghost!” Joe gasped.

  The boys went racing toward it, but the ghostly figure detected their approach and Bed.

  “That ghost must have eyes i
n the back of his head!” Joe muttered angrily, still running.

  The specter soon disappeared from view among the trees. Frank acted on a hunch. He shortcut back to the coupé and hid among some bushes. A white figure suddenly loomed out of the darkness. It headed straight for the car and yanked open the door. Before the phantom could climb inside, Frank pounced on him!

  The spook-masquerader battled wildly, but the other three boys quickly arrived on the scene and helped Frank pin him against the car.

  “Pretty solid for a ghost!” Chet remarked.

  “Not as solid as you,” Joe quipped. “But there’s flesh under that spook costume!”

  “Let’s have a look at him,” Frank added, and pulled off the prowler’s hood.

  CHAPTER XVII

  The Second Specter

  CHET let out a gasp of surprise as Tony shone a flashlight at the man’s face. “It’s that creep we picked up unconscious the other night!”

  “And also the thief who stole Iola and Callie’s amethyst,” Frank added.

  The man cowered in the glare of Tony’s beam. “Please, boys,” he whined, “I meant no harm. This ghost masquerade was just intended as a hoax. Nothing more than a joke.”

  “Some joke,” Tony said dryly.

  “How about stealing that amethyst?” Chet growled. “That was a joke too?”

  The man’s face turned pale. “No, it—it was wrong of me, tricking you with that oil smudge and snatching the stone right out of your house.” He wet his lips nervously. “But I had to have it! By rights, the stone belongs to me.”

  The boys were puzzled.

  “How does it ‘belong’ to you?” Joe asked.

  The man squirmed uncomfortably. “It doesn’t matter,” he mumbled, “You’ll find what you’re after in my right-hand coat pocket.”

  Joe reached inside the white robe. A moment later his hand emerged holding a purple stone.

  “The amethyst!” Chet exclaimed. Joe turned it over to him to give back to the girls.

  “You still haven’t answered my brother’s question,” Frank said in a cold voice. “Why did you say the amethyst belonged to you?”