"One thing is sure," he said. "Something made that man change his mind about the boat. You say it was an old tub and Chet paid him a good price for it. He wouldn't want it back except for a very good reason."

"Maybe it was because of that locked box in the bow," suggested Frank.

"Possibly," Mr. Hardy replied. "But I'd be more inclined to think someone else is demanding the boat."

"You mean the owner?" Joe inquired.

"That might be. Especially if the fellow stole it. But there may be even more behind it than that."

Mr. Hardy thought the strange open-faced Y carved on the gunwale of the sunken dory might be 98 the clue to the answer. After discussing the matter for some time, he decided it would be a good idea to raise the boat and examine it thoroughly.

"I believe the Bayport Salvage Company wouldn't charge much to do the work," the detective said. "Go over there tomorrow and ask for Mr. Redfield. Tell him I sent you."

Before going to bed, the two boys and their father went out to the kitchen for a snack.

While they were eating, Mr. Hardy told his sons he was grateful to them for finding the book which had been stolen from the Hamilton Museum. First thing in the morning he would drive to the little settlement where the constable was holding it, and compare the fingerprints on the book with some specimens he had taken from the gla.s.s cases at the Hamilton Museum.

"And now this weary man is going to bed."

At seven o'clock the next morning the Hardys were awakened by the persistent ringing of the frontdoor bell. Each member of the family appeared in the upper hallway, but Joe was first down the stairs to see who the caller might be. He opened the door to admit an excited young man.

"Is Mr. Hardy at home?" he asked, out of breath.

The detective hurried down the stairs. The man, who introduced himself as Doctor Mills, explained he was an intern at the General Hospital.

"Doctor Lyall sent me here to tell you something!" he cried out. "I was kidnaped last night to take care of a bandit!"

CHAPTER XII.

Mr. Hardy's Discovery.

the excited young intern was led into the Hardy living room, but he refused to sit down.

"I can't stay long," he said quickly. "Here's my story. I was on call last night at the hospital. A nurse came to tell me I was to go to the emergency entrance at once to help a friend of mine. When I got there someone ordered me into a car, and I was driven away."

The rest of the episode as told by Doctor Mills was similar to what had happened to Doctor Lyall. The main difference was that the intern could give no idea as to how long he had ridden, nor could he judge at what speed the car was driven to the place where he had treated a young man with a gunshot wound in his right leg.

The Hardys were discouraged that so far the intern had given them no clues. But hopefully they continued to quiz him for several minutes, and were about to give up, when suddenly he snapped his fin99 100 gers. He believed he did know something helpful.

"I did notice something that might help you. One of the bandits wore a very unusual signet ring. It was large, and on the top was a strange design, like three spokes of a wheel."

Frank, Joe and their father looked at one another. Frank grabbed up a newspaper, and in one corner of it sketched the strange, open-faced Y.

"Was it like this?" he asked the intern excitedly.

"Yes, it was exactly like that, I should say."

"Then you have given us a very valuable clue," Mr. Hardy told him.

"I'm glad," said Doctor Mills. "I'd certainly like to see those hijackers put behind bars.

They gave me the scare of my life."

The intern said he must leave. As he was going out the front door, Mr. Hardy said he would notify the police to warn all other interns, as well as medical students, to be on their guard against kidnapers. Then he turned to his sons, adding: "Boys, it begins to look as if we might be getting somewhere on this mystery."

Frank and Joe wanted to know if their father thought the kidnaper who wore the signet ring was John Mead. He told them his answer would depend on a telephone call he would make. It was not until the family was dressed and had finished breakfast that they got his reply.

"I've just learned," he said, "that a ring such as you and Doctor Mills described was stolen from a 101 museum some time ago. It's an ancient and very valuable ring."

"Whew!" whistled Joe. "Then I guess there isn't much doubt that fellow Mead we met on the road must be one of the museum thieves. And he seemed like such a nice person, too."

"He still may be all right," spoke up Mr. Hardy. "You know the old saying, 'A person is innocent until he is proved guilty,' and we haven't proved him guilty yet."

The detective announced he was going over to see Constable Pickens about the fingerprints on the book which had been stolen from the Hamilton Museum. Frank and Joe were disappointed. They had hoped their father would go to the Mead home with them, and said so.

"I was about to ask you for the key," Mr. Hardy said, a twinkle in his eye.

"You mean, sir, you don't want us to go with you?" Joe asked in disappointment.

"I was just testing you a bit," the detective replied. "You boys have so many mysteries you are trying to solve, I wondered if you were going to carry through on this one."

"Of course we are," said Frank. "Let's go!"

Father and sons set off immediately for the mysterious mansion on the bay. When they arrived there, Mr. Hardy walked over the grounds and made several notes before entering the house. He was extremely interested in the doors, remarking that it was 102 the first time he had ever seen anything like them.

"You boys did well to figure out the locations of these hidden locks," he said.

Frank opened the front door and led the way into the hall. He immediately felt for a wall switch and clicked it, but no light came on.

"Current's still off," he remarked.

The boys proceeded to show the detective the finely furnished interior of the house, using their flashlights when necessary. Mr. Hardy was not too interested in the decorations.

His eyes were hunting for clues to explain the connection between the house, John Mead, the key, the ring, and the museum thieves.

Frank and Joe admired the thoroughness of their father's search. In the hall, as well as in the other rooms, the detective ran his fingers over the walls expertly. Suddenly he paused at one corner of the library and surveyed the carved paneling. A moment later he moved aside the petals of a flower. To the astonished boys the dial of a wall safe was revealed.

The detective began moving the dial from right to left. Apparently his first try was not successful, because he stood silent before the safe for several seconds. Then once more he began to turn the dial. Half a minute later he grasped the handle on the safe, and the door opened.

"Dad! You're a wizard!" cried Joe, leaping forward. "How did you do it?"

103 Mr. Hardy did not reply. He flashed his light inside the safe, then closed the door.

"There's nothing in it," he announced in disgust.

"You think someone robbed it?" asked Frank.

"Perhaps, but then old Mr. Mead may not have left anything in it."

The detective looked off into s.p.a.ce. Frank and Joe knew better than to disturb their famous father when he was trying to work out a problem. Now, as he dropped into a chair, they too sat down and waited for him to speak.

"You want to know how I was able to open the safe," he said. "I a.s.sure you I do not use burglars' methods. I know that eccentric persons, such as old Mr. Mead, usually want to figure out things for themselves. Such a man would not use a combination which a safe company might offer. He would rather make up a combination of numbers himself, and what would you say would come to his mind first?"

"His name," Frank answered. "In the alphabet John would be 10-15-8-14."

"Possibly," said Mr. Hardy. "But in this case that was not what he used. Give another guess."

"His birthday," spoke up Joe. "But that couldn't be it, because you don't know when it is, Dad."

"You're right about what Mr. Mead used," said his father, "but you're wrong about the other. I took the trouble to find out when John Mead was born. It was October 15, 1870."

104 "The dial did turn to 10-15-18-70!" cried Frank, remembering. "But, Dad, how did you know when to turn the dial left or right, and in what order?"

The detective smiled, admitting that he had made a few failures before finding the correct sequence of the combination.

"And now I must be on my way to see Constable Pickens," he told the boys. "I believe you're going to the salvage company to find out about having Chet's boat raised? I hope you'll pick up something useful to our case."

Fenton Hardy dropped his sons at a bus stop on the highway, wishing them luck in their venture. Frank and Joe had a rather long wait, but at last a bus came along and they hopped aboard. The boys recognized a Mr. Dwyer, an old friend of their father's, seated in the rear.

He nodded pleasantly, motioning them to sit near him.

"Haven't seen you boys in almost a year," he remarked genially. "I understand you've been filling up the jails with criminals since I last saw you."

"We always try to do our bit," Frank told him, smiling.

"We've been getting a break," said Joe, and added, grinning, "We hope the criminals won't, though."

The boys asked Mr. Dwyer if he was still in the same business. The man told them he had gone into something different. He had helped organize a new boatbuilding company in Bayport, and as yet few people knew about the work.

105 "We're making small underwater craft."

"Submarines?" Joe asked eagerly.

"A certain type, yes," Mr. Dwyer replied. "But we are not working for the government.

We're making pleasure craft, and have sold a few already." Smiling, he added, "Maybe one of these days you boys will want to own one of them."

The Hardys said they certainly would. How exciting it would be to travel in a fast underwater boat! Frank believed that he had already seen one of Mr. Dwyer's craft. He told about the time he was looking for Chet's sunken dory, and had thought he saw a whale.

"No doubt it was one of our boats," said Mr. Dwyer.

As he was about to leave the bus, he invited the boys to accompany him to the factory, but they felt that it was important to go directly to the salvage company.

"Thank you just the same," said Frank. "We'll come another time if we may."

The brothers rode a few minutes longer before reaching the salvage company. Entering the office, Frank stated their errand. The man in charge looked puzzled. / / "Why, he's already gone on one of our boats," he said.

"Who has already gone?" asked Joe.

"That other man who was interested in the dory. Didn't you know he was coming?"

106 The Hardys said they certainly did not, and asked for more details. To their amazement they heard that a man had called at the salvage company early that morning, and had engaged their services to raise a sunken dory. Frank and Joe were positive it was Chet's boat.

"Are they out on the bay now?" Frank asked.

"Yes."

The Hardy boy turned to his brother. "We'd better get busy, Joe. Come on! We'll get the Sleuth and go after them!" and go after them!"

CHAPTER XIII.

The Puzzle of the Lights.

luckily a bus came along as the Hardy boys raced from the office of the salvage company. They hopped aboard, and not long afterward reached the boathouse where they kept the Sleuth. Sleuth.

Joe had the engine going in no time, and sped out into Barmet Bay. He headed for the spot where Chet's dory had gone down. No salvage boat was in sight. To the boys' dismay, they could see no sign of the Bloodhound, Bloodhound, though they circled round and round the vicinity, though they circled round and round the vicinity, peering down through the water, "They must have raised it!" Frank concluded.

"Now what'll we do?" Joe asked in disgust. "Go back to the salvage company?"

"Guess we'll have to," sighed Frank.

His brother headed the Sleuth Sleuth in that direction. They had gone only half a mile when in that direction. They had gone only half a mile when they spied the salvage boat just ahead. Hoping that Chet's dory was aboard, and that they could nab the man who had ordered it raised, the Hardys drew up alongside 107.

108 the salvage boat and hailed it. The larger boat stopped. The captain came to the rail.

"What's that you say?" he called down, not understanding Frank's request.

The boy repeated his question.

"Yes, I raised a sunken dory, but I haven't got 'er aboard," the man said. "I put 'er on the beach where the fellow who owned the dory told me to."

"But he didn't own it!" Frank cried.

The captain was astounded. He asked for more details, and upon hearing the whole story, told the Hardys where they no doubt could find the ill-fated boat. Without waiting for further discussion, Joe swung the Sleuth Sleuth toward the north sh.o.r.e of Barmet Bay. toward the north sh.o.r.e of Barmet Bay.

"Gee, we're sure running into bad luck," he said.