"Share equal," Chris said stubbornly. "Now you go down. Maybe you will find more. Maybe enough to buy me a new boat, and take good care of my father!"

Eagerly, Bob and Pete adjusted their face plates, made sure their breathing tubes were in working order, and slid into the water.

The sandy bottom was dotted with sh.e.l.ls. As they turned their lights this way and that, they saw nothing unusual. Then Pete spotted a shiny glint at the edge of the rocky wall. It was a gold doubloon, half buried in the sand.

Bob swam back and forth over the bottom with easy kicks of his flippered feet. A few minutes later he spotted a shiny object, partly hidden beneath an empty oyster sh.e.l.l. It, too, was a doubloon.

Excitement overwhelmed both boys. There really was pirate treasure in this underwater cave! Not handily stacked up in a nice, solid chest, maybe, but scattered over the bottom. There must be more and they would find it!

Heedless of the pa.s.sage of time, they scoured the sandy bottom. They turned over oyster sh.e.l.ls, making clouds of sand in the water and then having to wait until it cleared to search some more.

When they had found half a dozen gold doubloons each, their hands were too full to hold any more. Bob tapped Pete and they swam up and clambered out of the water.

Exultantly they poured their golden find on to a flat spot on the ledge.

"We found some!" Bob said excitedly. "Chris, you're right, there is treasure in this cave!"

Smiling, Chris reached behind him and produced three more doubloons. "I find these on ledge under the seaweed," he said.

"I'll bet there's more!" Bob said. "I don't know where it came from, but if we found this much we ought to be able to find some more."

"You've convinced me!" Pete said. "Come on, let's keep looking."

Treasure fever makes it impossible for a person to think of anything else. And the three boys certainly had treasure fever now. Heedless of time or any other consideration, they began to search the underwater cave. They swam along the bottom inch by inch, and explored every crevice of the rocky cave.

Even as they hunted however, something was happening that they couldn't possibly guess. Chris's sunken sailing-boat, nudged by the underwater currents, was being wedged into the eye-shaped mouth of the cavern. There it stuck, sealing up the entrance like a cork in a bottle.

The three boys were trapped in an underwater cave that n.o.body knew existed!

A Dangerous Predicament

JUPITER was worried. It was late in the afternoon and still Bob and Pete had not come back from their sail with Chris. What could have happened to them?

He got up from the desk where he had spread out all Bob's papers and the notes he had added to them. He plucked a tissue from the large box Mrs. Barton had provided.

Staring out of the window, he inspected the north end of the bay. There was no little sailing-boat in sight.

Mrs. Barton came in, bringing a gla.s.s of milk and some cookies.

"Maybe you'd like a snack, Jupiter," she said. "Lands, aren't those two boys back yet? Where can they be?"

"I don't know," Jupiter said, shaking his head. "They said they'd be back for lunch, and they're very reliable. Maybe they're in some trouble."

"Now, it doesn't pay to worry," the woman said. "Maybe they started fishing off one of the rocks and forgot the time."

She bustled out. Jupiter sat down and munched the cookies while he looked at his notes.

In his mind he tried to sum up the facts. Twenty-five years earlier, poor Sally Farrington's death and a ridiculous joke by some boys had started the legend of a phantom on Skeleton Island. For many years it apparently hadn't been seen. Then, beginning about ten years ago, it had been reported quite often, but always by an unreliable group of fishermen. As a result, no one went to Skeleton Island.

Then the movie company had come to fix up Pleasure Park and shoot some scenes there. They had run into a campaign of theft and sabotage that Jupiter felt sure was intended to drive them away.

Were the stories of the ghost somehow connected with the hara.s.sment of the movie company, or weren't they?

Jupiter was still struggling with this question when the door opened. Jeff Morton came in, looking very upset.

"Jupiter," he said, "have you seen Chris Markos?"

"Not since breakfast," Jupiter answered. "Pete and Bob went sailing with him. They haven't come back yet."

"Sailing all day!" Jeff exclaimed, his freckled face pink with anger. "But they borrowed two sets of aqualung equipment from me this morning and said they wanted to practice diving."

His features darkened.

"Do you suppose they're out diving with that crazy Greek kid, looking for treasure?"

He and Jupiter stared at each other in growing alarm.

"We'll have to go and look for them!" Jeff said. "Something may have happened to them. If anything has, on top of what's already happened " He didn't finish the sentence, but he looked grim. "Come on, Jupiter, let's get going!"

Jupiter forgot about his cold, forgot about the mystery, and everything else but finding Bob and Pete and Chris. He followed Jeff down to the waterfront, where a small boat with an outboard motor was tied to the pier.

They got in, the motor spun to life, and they roared out into the bay.

Jupiter wanted to ask Jeff what he had meant when he started to say "on top of what's already happened," but he was obviously in no mood for conversation. In any case, the roar of the motor made it difficult to talk.

They sped over to the pier on Skeleton Island where the bigger motor-boat was tied up.

"We'll need more room to bring the kids back when we find them," Jeff explained as they got into the bigger boat. "Also," he added ominously, "I want my gear handy in case I have to do any diving."

That could only mean, Jupiter thought gloomily, that Jeff Morton was afraid something had happened to the boys while they were diving. He tried to put the thought out of his mind.

Bob and Pete weren't reckless. They wouldn't have any crazy accidents. But he knew that not all accidents were due to recklessness. Sometimes something unexpected just happened.

Jeff swung the powerful motor-boat out into the bay and they began their search.

First Jeff circled Skeleton Island. Then he skirted up past the rocky reefs between the bigger island and The Hand. Finally he made a circle twice around The Hand.

"Nowhere in sight," he said to Jupiter, cutting the motor to idling. "That sailing-boat isn't in this part of the bay. The only other possibility I can think of is that the boys sailed over to the east side of the bay. We'll just have to go over there and cover every inch of the coastline."

Jupiter nodded. Jeff moved a lever, the motor took hold, and the boat started to roar away from The Hand.

None

Meanwhile, in the submerged cavern beneath The Hand, Bob, Pete and Chris crouched on the seaweed-covered ledge, dark water eddying round their waists. They didn't know how long they had been in the cave. But at the end where the blowhole was, the light had faded, and the tide had risen at least two feet.

They had been too excited at first to think about anything but the gold doubloons they were finding. They had gathered between forty and fifty gold pieces, which now filled the little canvas sack Chris had brought along for treasure. It wasn't a very big fortune, it was true, but an exciting find all the same.

Suddenly Chris had realized the tide was rising.

"We better get out of here," he told them cheerfully. "Anyway, we find all the gold, I think."

"We haven't found a doubloon for at least half an hour," Pete agreed. "And I'm starved. It must be awful late."

It was Pete, in the lead, who first saw the boat jammed in the entrance. It had slid into the eye-shaped opening on its side, its mast and flapping sail inward. The movement of the water had ground it into place and caught the tip of the mast in a crack in the rock.

Pete's flashlight picked up every detail. Less than a foot of s.p.a.ce was left between the boat and the rocks. They couldn't possibly sc.r.a.pe through there. They were trapped!

Together Pete and Bob swam against the boat and pushed. All they did was push themselves backwards in the water. The boat didn't budge. At that moment Chris came shooting between them. He saw the boat at the last minute, hesitated just long enough to take in the situation, then turned and swam desperately back into the cave. He had to surface and get another breath before the air in his lungs was exhausted.

Pete and Bob suddenly remembered that their own air was running low. They made another effort to push the sailing-boat out of the way, with the same lack of success.

Then they followed Chris.

A couple of minutes later they were all crouched on the ledge.

"Golly! We are in a jam!" Chris said. "Tide has that boat wedged in tight."

"It sure has," Pete agreed glumly. "Who'd ever expect a thing like that to happen?"

"I noticed the tide was moving the boat earlier," Bob put in. "But I never expected it to push it into the entrance. What are we going to do?"

There was a long silence. Then Chris said, "Tide is coming in now. Pushing boat in.

Maybe when tide goes out, water will push boat out again. We must hope so, I guess."

"But the tide won't turn for hours yet!" Pete groaned. "And when it does, suppose the boat doesn't move?"

"We've got a bigger problem than that," Bob said.

"Bigger problem?" Chris repeated. "What do you mean?"

"Look." Bob flashed his light upward. Just above their heads arched the roof of the cavern, wet and slimy with seaweed.

"See?" Bob said. "When the tide rises, this cave gets full of water. If we wait for the tide to turn, we'll be under water."

The rising water gurgled as it lapped around them. n.o.body had anything to say.

They knew Bob was right.

None

At that moment, in the motor-boat that was speeding away from The Hand, Jupiter gave a yell.

"Mr. Morton!" he called. "Turn back! I see something on the sh.o.r.e."

Jeff Morton frowned but swung the boat round. A minute later they were nudging up on a tiny sandy beach. Jupiter was out of the boat and running along the sh.o.r.e towards the rocks where he had glimpsed the boys' clothes. By the time Jeff had secured the boat and joined him, Jupe was excitedly rummaging through the now dry clothing.

"All their clothes!" he told Jeff. "They must still be here somewhere. Maybe they're diving on the other side of The Hand. I'll go and see."

Jeff Morton stared at the clothes in perplexity.

"The boat isn't here!" he exclaimed. "They've left their clothes and gone off in the boat with the diving gear for some reason. We "

But Jupiter wasn't there to listen. He was hiking up the hump in the middle of The Hand, moving much faster than he usually moved.

He reached the top of the ridge and eagerly looked down towards the other sh.o.r.e.

For a moment he couldn't believe there was nothing in sight. He had been so positive he would see his friends, or the boat. But they weren't there.

Dismayed, and realizing now just how badly he was worried, he slumped against a boulder. Jeff came puffing up beside him.

"We were all round this island," he said. "They aren't here, you should have known that. But where can they have gone?"

Angrily he picked up a small rock and flung it down. The rock landed in a slight hollow in front of them, rolled a bit, and went down a hole about eight inches across.

After a second, there was a faint splash down below.

Jupiter hardly noticed.