"Never had any trouble and didn't expect any. You see, we never followed the same route twice or went to the banks at exactly the same time. Just the same, one day "

What had happened was that one day, about ten years before, they had stopped to pick up money from the bank in Fishingport. Then they had parked the armoured car to eat lunch. Naturally it was tightly locked, and they sat where they could see it.

However, as Tom and the driver left the restaurant, two men wearing Hallowe'en masks had stepped out of an old sedan and shot the driver in the leg. Tom had lunged at the men, but they had smashed him over the head and shoulder with the barrel of the gun, knocking him unconscious.

Then they had taken the keys of the armoured car from his pocket, and driven off.

But Chief of Police Nostigon, then a patrolman, had heard the shot and came running in time to fire at the two as they climbed into the stolen truck. He hit one of the robbers in the arm.

The alarm went out promptly, of course, and all nearby roads were bottled up. At nightfall the armoured car, bloodstained and empty, was found in an abandoned boat-house some miles away. It became apparent that the thieves had made their escape by water.

During the night a Coast Guard patrol boat sighted an old motor-boat drifting helplessly in the bay. As they closed in on it, two men were seen to dump several bundles overboard. They sank immediately.

When the Coast Guard boarded the boat, they found two men, Bill and Jim Ballinger, ready to give up. Their engine had broken down, and one of them, Jim, had a bullet wound in his arm. But not a sc.r.a.p of money from the hold-up was found, then or later.

"You see, boys," Tom Farraday said, "they just chucked it overboard. Same thing old One-Ear did hundreds of years ago when he saw the British were going to catch him.

It went to the bottom, sank in the mud, and no one could find it. Being paper money, it rotted away mighty fast."

"Golly!" Pete said. "That was quite an experience, Mr. Farraday. Did the Ballingers go to jail?"

"Oh, sure," the guard replied. "With the bullet from Chief Nostigon's gun in Jim's arm, they never had a chance. They went up for twenty years, but it was reduced to ten for good behaviour. They just got out a couple of weeks ago. I'd certainly like to pay them back for crippling my left wing, boys," Tom said fervently. "Haven't been much use since then just odd jobs for me. Well, here we are and there's Mr. Crenshaw."

Pete's father and Jeff Morton were on the pier, stowing some gear into the big motor-boat. Mr. Crenshaw straightened as the boys came up.

"Hi, boys," he said. "Jeff is ready to check you out on your skin-diving. He's an expert diver and we have the very latest equipment here. He'll explain everything."

With that, Mr. Crenshaw left them, and the three boys climbed into the broad, roomy motor-boat.

"Okay, fellows," Jeff said. "Tell me what diving you've done."

Pete described the lessons they had had at a local swimming pool at home. They had become very familiar with snorkelling, and had been checked out by their instructor in Scuba diving just before coming East.

"So far, so good," Jeff said with an encouraging grin. "Now let's see how much you know."

He started the motor and ran the boat well out into the bay. Near a small yellow buoy, he dropped anchor.

"There's a wreck underneath us," he said. "No, it's not a treasure ship. Any old Spanish ship would long ago have disintegrated in these waters. This is a small yacht that went down in a storm several years ago. It lies in twenty-five feet of water, which means we can dive down to it without worrying about decompression problems."

He inspected and approved their face masks and flippers. Then, from a well-stocked equipment locker, he got out tanks of air, hose connections, and weighted diving belts.

"This is the latest equipment, and as nearly foolproof as it can be," he said. "We won't use wet suits because the water here is nice and warm. Get into your trunks, Bob, you'll take the first test dive with me. Remember, we'll be using the buddy system at all times always two divers together."

The boys got into their swimming trunks, and Bob carefully put on the equipment Jeff handed him. Last of all he buckled on the weighted belt that would come off if he had to make a fast ascent.

Jeff inspected him critically, nodded his approval, and got ready to go over the side.

Bob followed, using the special steps.

In the water, Bob kicked his flippered feet and shot downwards. He liked swimming. Over the years he had done a lot of it to build up strength in the leg he had broken as a small boy. Now, able to go down like a fish and breathe without difficulty, he felt wonderfully light and free, part of a new universe.

Below him a dark shape loomed up. It was the sunken yacht, and with Jeff at his side he swam slowly towards it.

The yacht lay on its side, a gaping hole near the bow. As they got closer, Bob could see that it was covered with seaweed. Small fish swam around it in swarms.

Jeff swam ahead. Using only his flippers to propel him, as he had been taught, Bob followed. Jeff swooned gracefully over the stern of the sunken yacht.

As Bob started to follow, his attention was caught by two large lobsters retreating beneath the stern. He swam closer to the sunken vessel.

Suddenly he was jerked to a stop. Something had him firmly by his right ankle!

"Don't Tell Anyone"

IT WAS the first time Bob had run into any trouble underwater. A pang of alarm shot through him and he kicked his leg to free it. The grip on his ankle tightened. He was sure he could feel himself being pulled backwards.

He turned frantically to see what had grabbed him, and as he did so, his arm brushed his face mask. The next thing he knew he was blinded. Water had fogged the mask and for a second he couldn't remember how to clear it.

Then something gripped his shoulder. For a moment he was sure the monster, whatever it was, was attacking him. But three light raps on his air tank told him Jeff Morton had come back to his rescue.

Jeff's hand gripped his shoulder, calming him. Gradually Bob relaxed, though it did not release him.

Forcing himself to breathe calmly, he turned his head to the right, reached up, and cracked the left side of his mask ever so slightly. Then he breathed out through his nose.

The air was forced out of the mask, taking the water with it, and he could see again.

The first thing he saw was Jeff Morton, shaking his head. He pointed, and Bob looked down to see what had caught him. A loop of rope!

He doubled over and eased the rope off his flippered foot. Angry at himself for panicking, he shot ahead a few feet and waited for Jeff, expecting him to end the dive immediately. However, Jeff formed a circle with his thumb and forefinger, a sign everything was okay. Then he swam ahead again and Bob followed, carefully keeping clear of the wrecked ship.

They swam the length of the ship, then all round it, the fish moving aside for them as if they were just two harmless larger fish.

Bob saw more lobsters sheltering themselves under the yacht. If he had brought a spear gun, he was sure he could have bagged a lobster or two.

They swam until Bob was relaxed again and enjoying himself, then Jeff headed for the surface at an unhurried pace. They could see the bottom of the anch.o.r.ed motorboat. A moment later they came up beside it, their masked faces popping from the water like the snouts of some strange monsters.

Jeff swam to the steps at the side of the boat and climbed it. Bob followed.

"How was it?" Pete said eagerly, helping him in the boat. Bob shook his head.

"I didn't do so well," he said. "I got snagged on a rope, and got panicky."

Jeff Morton agreed that he hadn't done so well. He gave them all a brief lecture on getting too close to tangled wreckage, and followed it with one on losing your head in an unexpected situation the most dangerous thing a diver could do. Then he relented and smiled.

"Maybe it was a good thing it happened now," he said. "A harmless but helpful lesson. Bob recovered himself well and next time I'm sure he'll keep calm. All right, Pete, now it's your turn."

Pete got ready swiftly. In a moment the two divers were gone beneath the water, leaving Bob and Jupiter alone in the gently bobbing motorboat.

Bob told Jupiter of his experience in more detail, adding, "I think next time I go down I'll have more confidence. Now I know I can make myself act calm and clear my face mask if I have to."

Jupiter was about to reply when they heard a voice hailing them. A hundred yards away, the tiny sailing-boat owned by Chris Markos was gliding silently towards them.

Chris came up beside them and swung round, letting his sail flutter down. His white teeth gleamed against his tanned face as he grinned at them.

"That fellow Tom Farraday tells you bad things about me, I guess," he said, his smile vanishing. "I hope you don't believe him."

"No," Bob said stoutly, "we don't believe him. We think you're all right, Chris."

"I am glad to hear that," Chris declared. He reached out and caught the side of the motorboat to steady his craft.

He looked at the variety of diving gear in the motorboat with some longing, but said airily, "Why do you need all that stuff to dive down to sunken yacht? I can go down that far just in my own skin. I'm a real skin-diver! "

"Is it true that Greek sponge fishers can go down more than a hundred feet without any diving apparatus?" Bob asked.

"Sure, easy," Chris boasted. "My father when he is a young man, he goes down two hundred feet with just a stone to make him sink fast, and a rope to pull him up again.

He stays, under three whole minutes without breathing." Chris's face clouded. "But he dives too long," he said. "And he gets sick. But some day I find treasure, take my father home, get a little boat in Greece and be a fisherman myself."

Chris's smile came back. "Got to get busy. Keep looking if I wish to find treasure,"

he said. He hesitated, then added, "Maybe I take you with me tomorrow if you like to go? Nice fun even if we find nothing."

"That would be great!" Bob said. "If we aren't needed, that is."

"We might have to do something for the movie company," Jupiter added. "Or practice diving some more."

Then he surprised them, and himself, by giving a mighty sneeze.

"Are you catching cold, Jupe?" Bob asked.

"Do not dive if you have cold!" Chris warned. "Ears hurt fierce. Well, so long, I must get busy. See you tomorrow, maybe."

He let go, hoisted his sail, and in a moment the little boat was skimming across the sunlit surface of the bay.

A few minutes later, Pete and Jeff Morton surfaced and climbed aboard. Pete shucked off his gear, grinning widely.

"It was terrific," he said. "Had a little trouble clearing my eustachian tubes, but I swallowed hard and that fixed them up. Now it's your turn, Jupe."

Jupe got ready a little less eagerly than the others. Jupe was not naturally athletic, and though he liked swimming all right, he was not really keen on it. When he was ready and had pa.s.sed Jeff Morton's inspection, he and Jeff slipped over the side.

"Bob!" Pete said excitedly as the other two vanished under the water. "Guess what?"

"What?" Bob asked.

"I think I saw something. Just as we were turning to come up, I saw something gleaming on the sand about fifty feet from the sunken yacht. I bet it's a gold doubloon.

If we dive again I'm going to try to find it!"

"Wow, are you sure?"

"Not positive. I just got a glimpse of something bright. But it could be. Everybody says there's treasure scattered loose all over the bottom of this bay."

Bob started to reply, then stopped. Jeff Morton and Jupiter were already coming back up! In fact, Jeff was helping Jupiter, who was swimming blindly, his face mask twisted to one side of his face.

"What happened?" Bob asked.

"Nothing to be alarmed at," Jeff said. "Somehow Jupiter knocked his face mask loose. I don't know how but we weren't down far and he didn't lose his air hose."

The two climbed aboard, Jupiter looking miserable.

"My ears hurt as we went down," he said. "I tried to swallow to open the eustachian tubes. Then I had to sneeze. I pulled out my mouthpiece and held it, but I had to move my face mask to sneeze and I couldn't put it back again and well, I guess I didn't do too well," he finished miserably.

He sneezed again.

"You're catching a cold," Jeff said sternly. "You should never have tried to dive today. Lucky we were only down a few feet. No more diving for you, my boy, for the next few days!"

"No sir, I guess not," Jupiter said humbly. "The air conditioning on the plane yesterday was pretty chilly and then being out in the storm last night well, I guess I'm catching a cold all right."

"Never dive unless you're in excellent health," Jeff said. "Especially not if you have a cold or cough. Well, I'm supposed to give you kids practice in diving and I'll go ahead with Bob and Pete, but if you're going to be laid up, we may have to change our plans."

For the next couple of hours, Bob and Pete alternated in longer and longer dives. By the end of the afternoon they felt weary, but were sure they could handle any simple underwater diving that might be required of them.

On each dive, Bob kept his eyes open for the shiny thing Pete said he'd seen, but he didn't spot it. On the last dive of the day, though, Pete came up with his right hand tightly clenched. He scrambled aboard and hastily removed his face mask and mouthpiece.

"Look!" he said exultantly.

He opened his fist. On his palm lay a worn but shiny round coin, large and heavy.

"Holy cats!" Jeff exclaimed. "A doubloon!" He examined it carefully. "Dated 1712, and Spanish, all right. Pete, whatever you do, don't let anybody know about this. I mean, besides us and your father."

"Why not?" Pete asked, puzzled. "You mean someone would try to take it away from me?"