Rick tugged at Scotty's suit, then crawfished backward through the marsh grass until he was sure the night watchers could not see him. He stood up, and Scotty joined him. Rick motioned toward their own boat.

The boys made their way back through the swamp to the runabout in almost total silence, each busy with his own thoughts.

Orvil Harris was crabbing as though nothing had happened, while the night watchers stood in plain sight on the opposite shore. Orvil must have seen the shots fired, Rick was certain. Even if he had been looking the other way, the first shot would have caught his attention.

Or, Rick wondered, had Orvil tipped off the two guards that divers were below? If so, the game was up. Once Merlin and company knew the payload had fallen into the cove, they would be diving for it themselves, under cover of guns. Merlin undoubtedly knew that the launching the evening of the squall had gone wrong, but he couldn't know how, or where.

But somehow, Rick didn't think Orvil had been a party to the shooting. Maybe it was stubbornness, refusing to think the crabber was involved just because they liked him. Or maybe it was because the crabber had no reason for helping Merlin and his gang; at least Harris had no reason known to Rick and Scotty.

They reached the boat and conferred in whispers that were inaudible six feet away.

"Could Orvil have put the finger on us?" Scotty questioned.

Rick shrugged. "I don't want to think so, and I don't. But I have to admit it's possible."

"If he's in with them, they'll be diving for the 'what's-it' at first light."

Rick glanced at the eastern sky. It was beginning to glow with the first hint of daylight. "That's not long from now."

"How are we going to recover it first?"

Again Rick shrugged. "There's only one way. Go in and get it."

"Under those guns?"

"A diver on the bottom isn't in danger from the guns. I could find the thing again without going into the shallows. That's what made us targets before, because we took the easy way to locate the fish line by going into the shallows near where I tied the line."

"Let's see your tank," Scotty whispered.

Rick unsnapped his harness release and swung the tank around. Their probing fingers soon identified where the bullet had glanced off. There was a dent, coated with silvery metal.

"Lead," Rick said. "Part of the slug."

"Good thing it didn't rupture the tank."

Rick shuddered. "If it had, I'd have been out of air suddenly and would've had to come up. Listen, Scotty. My plan is a simple one. I'll take your tank, since you have the most air, and swim right into the cove, find the 'what's-it' and swim out again. If it's too heavy to tow far, I can at least wrestle it part of the way, and then bury it in the mud. Meanwhile, you get the boat out where it's clear and be ready to pick me up."

"They'll see your bubbles, but they can't do anything about it with rifles," Scotty pointed out. "One thing they can do, though, is jump in after you. The cove isn't so deep that a pair of good swimmers couldn't tackle you. The lung wouldn't improve your chances by much."

"Too true," Rick observed. "But what else can we try?"

Scotty thought it over. "Listen, we'll take the boat out right now. You'll have to do the diving, because you know about where the thing is, and I don't. When we get out, you go over the side. I'll run around to the river, opposite where the guards are standing, and raise a little fuss. That might draw their attention away from the cove."

"Okay." It made sense to Rick. "They'll see both of us in the boat, but they won't see me get out. Only you'd better plan our course. I have no aching desire to collect a rifle slug where it hurts."

"They may not shoot if they see we're leaving," Scotty pointed out.

"Uh-huh. And they might shoot, anyway."

"They might. But we'll be moving fast, and I'll swing that boat from side to side like a swivel-hipped fullback. Let's get going. We don't want too much daylight."

Scotty unsnapped his harness and Rick took his pal's tank and regulator. They put Rick's unit in the bottom of the runabout cockpit, along with Scotty's fins and mask. Rick put on his own fins and made sure he was ready to hit the water at a moment's notice.

Rick went to the stern of the runabout and felt down the motor leg to the prop to make sure it had not picked up any grass that might slow them down. It was clear. Scotty, meanwhile, untied the boat and slid into the driver's seat. Rick reached over the transom and pumped up the gasoline tank to ensure plenty of pressure, then he waded to the side of the boat and got into the seat next to Scotty.

"Pull us out to where the nose is almost projecting beyond the grass," Scotty whispered.

Rick did so, by grasping clumps of marsh grass and pulling the boat along. As the bow cleared the grass, Scotty punched the starter button, threw the runabout into gear, and shoved the throttle all the way forward.

The runabout jumped forward, slamming Rick back against his tank. The boat hit the shoal at the entrance and slowed for a long, breathtaking moment, then the driving prop pushed it over into deeper water. The stern went down and the bow lifted, and they were clear.

Scotty swung the boat to the right, putting its stern to the cove. Rick tensed, expecting any moment to feel the impact of a rifle bullet, either in the boat or in his own body. There was no sound other than the racing motor, and he knew it would drown out the crack of a distant rifle.

The distance from the cove entrance widened. "Get ready!" Scotty yelled. "Lay flat and be ready to roll. I'll turn so the motor is moving away from you. When I tap you, we'll be directly in line with the cove entrance."

Rick moved out of the seat, keeping low, and lay on his side along the gunwale, facing Scotty. He put the mouthpiece in place and made sure he was getting air, then pulled his mask down. He was ready. The impact with the water would be hard, at this speed, but his tank would cushion the shock. He tensed for the signal.

Scotty swung the boat to the left, held it on course for a moment, then began a shallow turn to the right. That way, the motor would be steering itself away from Rick when he went over.

The boat came abreast of the cove entrance and Scotty slapped Rick on the shoulder. Instantly Rick rolled, one hand reaching for the back of his head, the other grabbing his mask. He hit the water on his back, his hand and the tank breaking the shock of the stunning impact. He threw his legs upward, and his momentum took him under the water instantly.

The racing motor receded, leaving him in silent darkness. He rolled over into normal swimming position and consulted his wrist compass. The creek entrance ran on a course of 80 degrees. If Scotty had gauged things correctly, that course would take him into the cove. If Scotty hadn't, Rick Brant would end up on the beach like a stranded whale.

Rick considered. The boat was gone, and it was extremely unlikely anyone had seen him leave it. The turn had caused the boat to tilt, lifting the side away from him. He was certain that the guards had not seen the maneuver. That being so, and taking into account his distance from the creek entrance, he thought it would be safe to look and check his course.

He held the compass in front of his eyes, and rose to the surface. He broke through slowly and without a splash. One look was enough. He should have trusted Scotty. He was dead on course.

Rick went to the bottom and began the long swim, counting his leg strokes. He and Scotty had practiced estimating underwater distance by the number and timing of their leg strokes. It wasn't an exact method, of course, but it was practical.

There were no underwater obstacles, and the depth was great enough. Rick remembered from the chart that the entrance into the creek varied from eight to eleven feet, dropping inside the creek mouth to about seven. No bullet could harm him if he stayed on the bottom. If the night watchers fired, the bullet would be slowed by the water.

He heard the sound of a motor and recognized it as the runabout. The sound faded again. Scotty was going through some kind of maneuvers. Then, in a short time, another motor made itself felt, more than heard. The slower beat identified it as Orvil Harris's crab boat. He was nearing the cove!

Like all divers, Rick's ears were sensitive to pressure changes. Sensing when the depth lessened, he knew he had reached the cove itself. Now to find the payload—if it was a payload. His groping hands began the search.

The first foreign object he touched was a cord. It was the wrong thickness for his own line, and he felt along it until he came to a soft, round mass, and knew he was touching one of Orvil's crab baits. He grinned in spite of the mouthpiece. Wouldn't Orvil be surprised if a diver came up hanging to his bait!

He let the crab line drop and continued his search. Once, Orvil passed within a few feet of him, and Rick wondered if the crabber had noticed the air bubbles from his regulator.

Rising ground told Rick he had reached the end of the cove. He turned left and held his course for about twenty feet, then turned left again, heading back toward the cove entrance. His hands never stopped moving, probing the mud for a trace of fish line. He crossed another of Orvil's crab lines, and kept going until pressure change told him he was back in the deeper water at the creek entrance. He turned right again. A check of his compass told him he was on course.

His groping hands trailed over a thin line. He grabbed it, and stopped his flutter kick. Then, moving with care, he turned and followed the line. His pulse was faster now, and he rigidly controlled his breathing. Fast breathing wouldn't do, and he would have to be careful not to let out a sigh that would cause bubbles to gush upward in one big rush.

A hand found the end of the line and the smooth cylinder to which it was attached. Orvil passed very close, and Rick looked upward. He could see the white circle of water around the single propeller.

Now to find out what he had. His hands stroked it from one end to the other. One end was rounded. The other was a circle with an odd-shaped hole running into it. Rick poked his finger in, but couldn't feel the end of the depression. The only protuberance on the thing was a band near the rounded end. The band felt like metal, and had two rings projecting from it. The rest of the cylinder didn't feel like metal. The texture was that of a smooth plastic.

Rick lifted the object gingerly. It was hard to estimate weight under water, but he thought ten pounds would be about right. The total length was less than three feet. It would be easy to carry.

This time he needed a reciprocal compass course. It would be 260 degrees going out. He oriented himself properly, picked up the cylinder, and began the long swim back. He wondered if Merlin's guards were watching his bubbles. He had seen no sign of bullets, but he hadn't been looking for them. With Orvil's motor so near, it was likely he would not have heard the slap of a bullet on the water.

Pressure told him he was out of the cove. He breathed a little easier. Now to count leg strokes again. He looked up, and saw that the surface of the water was shining with light, the first rays of true daylight. Scotty would have no trouble finding him.

Because of the daylight, he continued on for a distance beyond where Scotty had dropped him. No use giving the guards too good a shot. Finally, exhausted, he surfaced. He lifted his mask and surveyed the scene.

Orvil Harris was still crabbing. Rick could see the boat, but the angle was wrong for him to see the crabber at work. He turned slowly in the water, and saw Scotty. The runabout was floating, motor off, about a mile away. He lifted an arm. The glint of first sunrise turned the lenses of Scotty's binoculars into a crimson eye, and Scotty waved back. In a few seconds Rick heard the motor start and saw the boat racing toward him. He kept his mouthpiece in place, and floated, waiting.

Scotty came alongside and reached down. Rick handed him the cylinder. Scotty put it on the seat without even looking at it. He gave Rick a hand and pulled him over the side. He asked anxiously, "Are you all right?"

"Done in," Rick said wearily. "But otherwise okay."

"Let's get out of here." Scotty put the runabout in gear and headed back toward Martins Creek.

Rick sat down and picked up the cylinder. There was a gob of mud still on it. He wiped it off with his hand and examined the thing. The material was fiber glass set in resin, and it was designed so the rounded nose could be removed. He didn't remove it, however. Instead he looked at the other end, down into the hole with the puzzling shape. It was like a cutout Star of David in shape, the hole gradually narrowing until its apex was almost at the other end.

The light dawned. Rick's lips formed the word. "Grain."

Scotty was watching. "What?"

"Grain," Rick said again. "This thing is a small solid-propellant rocket!"