Frank's guess seemed to be correct, for as the Hardys closed in, he gave up his search and fled into the woods. Joe would have chased him, but Frank grabbed his brother's arm and pointed to
Skyhappy Sal.
Flames were licking the fuselage!
“Never mind that guy! Help me get Jack out!”
The right side of the plane, from which the gunman had been thrown, was uppermost. The door was hanging wide open. Frank climbed inside, careless of the sizzling flames. Jack lay wedged behind the control column, bleeding and motionless.
“He risked his life to signal us!” Frank thought. “I sure hope he's still alive!”
There was no time to be gentle. Frank maneuvered the limp form out as best he could. Legs first, Jack was passed through the cabin doorway Both the Hardys were streaming with perspiration as they lurched away from the plane, lugging the pilot between them.
At a safe distance from the wrecked aircraft, they laid Jack down on the sand and turned back to stare at
Skyhappy Sal.
The blaze was now crackling furiously.
“Some of the electrical gear must have shorted,” Joe said.
“We'll never know,” Frank muttered. “Once the fuel tank blows, she'llâ”
His words were cut short as the plane exploded into a ball of fire. A column of smoke and flame shot high in the air.
“Wow! We made it just in time!” Joe gasped in a shaky voice.
The boys turned their attention to Jack Wayne. His face and shirt were streaked with blood from a scalp wound. Frank felt the pilot's pulse and knelt to listen for a heartbeat.
“Thank goodness! He's still alive!” Frank reported tensely.
Joe ripped off a piece of his own shirttail to make a bandage. Fortunately, although the pilot's hair was matted with blood from the wound, active bleeding appeared to have ceased.
Frank wiped off Jack's face with a scrap of cloth moistened with water. Presently the pilot stirred and opened his eyes. As he saw Frank and Joe bending over him, his lips twitched into a smile of relief.
“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 usâis 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 toâ”
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'tâ”
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 planeâthe 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 speedâheading 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 shapeâno 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 eachâone 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 elevatorâbut not to the fifth floor. And O'Bannion did deliver the gemsâbut 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 floorâor possibly the fourth.”
“How do you figure that?”
“The watchman blacked out twice,” Frank replied. “During that time, someone could have tampered 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 doorsânot 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 beforehandâand the person inside wouldn't know the difference-even the watchman himselfâunless 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. OâBannion rings from Six, but the light shows Five. Mike pushes the button for Fiveâbut 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?”
“Yesâprobably 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 isâhow 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, Joeâwhat did that remark you heard on the tunnel phone mean?”
“About the âdisappearing floor'? I have a hunch it referred to the Haley Building job.”
“That's one possibility. Actually, there are
three
âdisappearing floors.' Oneâthat phonily numbered floor at the Haley Building. Twoâthe hinged tiled summerhouse floor. And threeâthat 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.