"You're right," he said, "I guess we just have to try the east sh.o.r.e of the bay. Though I can't imagine why they'd leave their clothes here."

Jeff stood up. "Come on, we'd better get a move on. I think we should call the Coast Guard to come and help us look. It'll be dark and we'll need all the help we can get!"

Jeff started back for the motor-boat and Jupiter followed. He knew Bob and Pete and Chris were in trouble. In his imagination he could hear their voices calling for help, and he couldn't answer because he didn't know where they were. He could almost hear them, as if "Golly!" Jupiter whirled around and started back, his legs pumping hard. He ignored Jeff's startled shout as he ran to the little hole in the rock, the blowhole, and flung himself down beside it.

With his face directly above the hole, he shouted, "Bob! Pete! Are you down there?"

There was silence. Jupiter, his heart pounding, realized it was a crazy idea. They couldn't possibly be down under this island.

Then up out of the blowhole, m.u.f.fled but clear, came Pete's answer.

"Jupe! We're in a jam! If the tide rises a little more, we'll be under water. Get us out of here!"

Jupiter Thinks Fast

IN THE CAVE the boys held tightly to the seaweed on the rocky ledge. Otherwise the water that was up around their shoulders would have floated them away. It was rising fast. Soon they'd have to swim and keep swimming, until the rising tide squeezed them right up against the roof.

"I wonder what's taking them so long?" Pete muttered, shivering a little. It seemed like a long time since the stone had unexpectedly come down the blowhole, and he and Bob had started yelling for help.

When they hadn't got any answer, there had been a bad minute in which they figured the rock had just rolled down by itself. But they kept on yelling, and then Jupiter's voice answered them.

After Jupiter, Jeff Morton had called down. It took a couple of minutes of yelling back and forth before they could get him to understand the situation. As soon as he realized the fix they were in, he shouted that he would get help for them fast. Then he and Jupiter went away.

Now the three boys were waiting for the promised help. Bob kept his light turned on, though the batteries were running down, because even the dim glow helped in the darkness.

"Listen!" said Chris. "We do not tell about gold doubloons. We keep that secret for now, yes?"

"Why?" Bob asked. "We'll have to explain what we were doing in here."

"Everybody with diving gear will come to explore cave," Chris protested. "We do not get the chance to come back and look some more."

"As far as I'm concerned," Bob said, "I never want to see this cave again. I don't care how much treasure is in it. Let somebody else have it."

"I'll buy a double helping of that," Pete agreed. "Anyway, I think we found all there is. Just some doubloons that got washed in by the tide."

"But maybe there is some more!" Chris argued. "It is my big chance to find treasure to take my father back to Greece. What we have, only forty or fifty doubloons, is not nearly enough, especially when we divide up."

"Well," Bob said, "maybe we can keep it a secret. We can try, for your sake. I guess you're right about people coming to search this cave."

"Pete Crenshaw won't be among them!" Pete said fervently. "But if you want to come back, Chris, well, we'll just say we found the doubloons in the water. That's true enough. We won't say where."

"I keep doubloons secret if I can," Chris said. He clutched the canvas sack which held the coins. "I am not afraid to come back. The way we got caught would not happen again in a million years."

"Once will be enough if Jeff Morton doesn't hurry!" Pete groaned. "Golly, do you suppose he's going to have to go all the way to get the Coast Guard?"

"He'll need some help to get that sailing-boat out of the mouth of the cave," Bob said. "I'm almost sure he can't drag it loose by himself."

"But that could take a couple of hours!" Pete exclaimed, grabbing at the seaweed as a surge of water almost washed them from their slippery perch. "The tide will be in and this cave will be full by then!"

"Jupe will think of something," Bob said hopefully. "You can't beat Jupe in an emergency."

"I hope you are right," Chris said, in a very low voice. "But it sure is taking a long time!"

Actually, it had been only fifteen minutes since Jeff Morton and Jupiter had left the blowhole above and hurried back to the motorboat. Now the boat was idling a hundred feet offsh.o.r.e, with Jupiter handling the controls while Jeff got as swiftly as he could into an aqualung outfit.

"Crazy kids!" he muttered, as he strapped on his weights and prepared to step over the side of the boat. "How in the d.i.c.kens could they get into such a fix?"

He turned to Jupiter.

"All right, Jupiter, hold the boat steady right here," he said. "I'm going down and see what the situation is. Probably I can ease the sailing-boat out of the way. Anyway, I hope so. I don't want to have to go for the Coast Guard."

He pulled his face mask into place, grabbed an underwater flashlight, and went over the side. Jupiter felt very much alone. In the distance he could see boats heading for Fishingport from the south end of the bay, but none came anywhere near him. The minutes went by very slowly as he waited for Jeff to come up again. When it seemed like an hour, he looked at his wrist.w.a.tch and saw that only five minutes had pa.s.sed. Another five minutes went by. Then Jeff Morton's head popped up right beside the boat. He climbed aboard, looking grey and anxious.

"That boat is jammed in the cave entrance, all right," he said. "As neat as a cork in a bottle. I got a grip on it and pulled but I couldn't budge it. It's a job for the Coast Guard. We'll need divers with crowbars either to break up the sailing-boat or pry it out of there."

Jupiter stared at him.

"Won't that take too long?" he asked tensely. "I mean, a couple of hours, perhaps?"

Jeff nodded slowly.

"All of that," he said. "I know what you're thinking. The cave will be full of water by then. But I don't know what else to do. If that blowhole was big enough, we could lower a line down it and pull them up. But it isn't."

Jupiter was pinching his lip, which always helped him think. Now an idea was coming to him.

"Mr. Morton!" he exclaimed. "Maybe we could pull the sailing-boat loose!"

"Pull it loose?" Jeff frowned at him. "How?"

"With the motorboat!" Jupiter said. "It has a powerful motor. We have an anchor and plenty of rope. We could hook the anchor on to the sailing-boat. Then if we give the motor full power straight ahead "

"I'm with you!" Jeff exclaimed. "By George, it might work. Come on, we have to move fast!"

Working swiftly, he untied the anchor rope from the bow, brought it back and attached it to a ringbolt on the stern. Then he dropped the anchor overboard, paying out all the rope.

"There!" he said. "A hundred feet of rope should be enough. Now I'm going back down to attach the anchor to the sailing-boat. When I tug on the anchor rope three times, ease the boat forward until the rope is taut. Then slowly give it full power. I'll be down there trying to help ease the sailing-boat out.

"If you feel a give, followed by a slow heavy drag, that'll mean you have the sailing-boat loose. Pull forward a hundred feet or so, then cast loose the anchor rope and reverse to come back to position. I'll swim into the cave and get those kids out.

"If you feel a tug, then suddenly you jerk free, you'll know the anchor came loose.

Stop and wait for me to come up. But pray your idea works the first time! "

Jeff climbed over the side and was gone into the depths again. Jupiter waited, his heart beating anxiously, the anchor rope in his hand. He felt a pull on it, but that was only Jeff recovering the anchor and carrying it back to the cave. A minute pa.s.sed, two-then he felt three sharp tugs on the rope.

Jupiter moved the boat ahead until the anchor rope was a taut, straight line from the stern down into the water. Then, ever so easily, he increased the power.

The motor began to roar. The propeller threw up a wash behind him. But the motorboat did not move. Jupiter increased power, his heart in his throat for fear the anchor would tear through the side of the sailing-boat.

Very, very slowly, the motorboat began to move. Sluggishly, as if pulling a whale, it gained distance. It was dragging a dead weight across the bottom, and it had barely enough power to move it. But it did move.

Twenty feet fifty feet a hundred feet!

Jupiter would have cheered if he had not been so intent on the job. He threw the motor controls into neutral, and with his prized Swiss pocket-knife reached back and cut the anchor rope. The rope slithered down into the water. Jupiter gave the motor reverse power and eased back into position.

He tried to imagine what was happening below. The cave entrance was open now. Jeff was swimming in. He had found the three boys. Now he was instructing them to swim out and surface. In a minute or two minutes.

A head popped out of the water just behind the boat. It was Chris Markos. He thrust up his face mask and breath exploded from his lungs. He paddled over to the motorboat, grabbed on to it and pushed something heavy over the side. It dropped at Jupiter's feet with a clink.

"Hide it, Jupe !" Chris gasped. "We find treasure. But we keep it a secret. For now, anyway. Tell you all about everything later."

Jupiter hid the wet bag the best way he could think of. He sat on it.

"Boy!" said Chris when he was safely in the motorboat. "We are sure afraid you can't get us out in time. Pete and Bob, they will be up any second."

Just then Bob's head appeared, and a second later, Pete's.

"It sure was good to hear your voice down there," said Pete when both boys had clambered aboard. "Yours and Jeff Morton's."

"He's pretty angry at us," Bob said. "I guess he has a right to be."

"When he talks to Dad, Dad will be angry, too," Pete said dolefully. "But anyway, we found some treasure. Did Chris tell you?"

"I'm sitting on it," Jupiter said. "You can tell me all about it later."

"I guess we're going to get a good bawling out," Bob said easing himself out of his gear. "But it actually wasn't our fault. First somebody sank Chris's sailing-boat, then "

"Here comes Jeff Morton now," Jupiter interrupted him. "He'll want to hear what happened."

Jeff had surfaced at the stern of the motorboat. In his hand he had the severed end of the anchor line. When Jupiter had grabbed it and attached it to the ringbolt, he swam round to the steps and climbed on board.

He removed his face plate and slowly took off his weights and air tank. Then he looked at the silently waiting boys.

"Well," he said at last, "I'm glad you boys are safe. Plenty glad. But that doesn't alter the fact that you acted recklessly and got into serious trouble."

"But " Bob began. He was sure that if he could explain just how it all had happened, Jeff Morton would see that there wouldn't have been any danger except for the freakish current that had wedged the boat into the cave entrance.

Jeff held up his hand. "I don't care what your explanations are," he said. "Facts are facts. When I tell Harry Norris and Mr. Crenshaw what's happened, I'm sure they'll agree with me that you kids aren't to do any more diving.

"It was a bad idea to begin with the water in this bay isn't really clear enough to get good underwater pictures. Harry Norris agrees with me, and I'm sure Mr. Denton will when he gets back here. So that idea of a short subject showing you diving for treasure is washed up."

He paused for breath, but it was plain he had more to say.

He turned and faced Chris.

"However," he said grimly, "I think one source of our troubles is ended. We've discovered who's been tampering with our equipment, stealing things, and giving us such a headache. Last night the equipment trailer was broken into through a small window, too small for anybody but a boy to get through. Someone stole two lenses worth almost a thousand dollars. I discovered the lenses missing and I found something else. Something the thief dropped by accident."

His eyes bored into Chris's.

"I found your knife, Chris," he said. "Where you dropped it when you stole those lenses. n.o.body else but you could have slipped through that tiny window.

"I've already reported the facts to Chief Nostigon, and when we get back to Fishingport, I'm marching you down to the police station. I'm very much afraid that you're going to jail!"

Jupiter Solves One Mystery

"BOY, WE SURE are in the doghouse!" Bob sighed.

"We're in the doghouse, but Chris is in jail," Pete said gloomily. "I don't think he stole those camera lenses, do you, Jupe?"

Jupiter didn't answer. He was sitting on the sofa in Mrs. Barton's living room, a far-away "thinking" look on his face. It was the middle of the afternoon and outside a heavy rain was pouring down. The boys had been ordered not to leave the house by Mr.

Crenshaw, who had given them a severe lecture about irresponsibility the previous evening.

"Jupe!" said Pete more loudly. "I just said I don't believe Chris stole those camera lenses. Do you?"

Jupiter coughed. His cold was still bothering him.

"No," he said, "I don't. One kid can generally tell when another kid is sneaky and Chris isn't sneaky. It's just that appearances are against him. His knife being found at the scene of the crime is very peculiar."

"He lost it two days ago," Bob pointed out. "He said so."

"And of course the men wouldn't believe him," Jupiter said, coughing again. "They want to think the mystery of Skeleton Island is solved, so they believe he did it. That's the way adults often are."

"Well, what is the secret anyway?" Bob grumbled. "We're investigators and we ought to be able to at least make a guess."