CLOUDS SWEPT ACROSS the yellow oval of the moon, one moment obscuring it, the next opening chasms so that its ocher light could stream down upon the plain of black ocean beneath. The moon hung motionless, while around it the clouds roiled. It was as if they possessed a life of their own, whirling upon themselves, breaking into pieces and attaching themselves, leechlike, onto others. They were first the maws of fantastic monsters, then men's faces with mouths open and screaming, then bare, bleached skulls shattered slowly into fragments by the Caribbean winds.

There were two lights panning across the surface of the sea - one high, over a dark mass of land, flashing intermittently, and the other floating low, just above the stern of a rusty-hulled American freighter hauling eight thousand tons of raw sulfur.

And one hundred yards beyond the freighter's wake was something else.

Quietly and smoothly a dark cylinder of iron rose up from the depths on a slender tower. The metal had been painted black to avoid reflection, the viewing lens sheathed in concrete - a single freezing eye.

The periscope turned, the only noise betraying its presence a soft hissssss of foam rushing around the tower; it sighted the island beacon, paused a few seconds, and turned several degrees to study the specter of the merchant vessel. Moonlight glittered off railings, off porthole rims, off the glass in an upper-deck wheelhouse.

Easy prey.

The periscope descended. A gurgle of water and gone.

Then, with a noise like the death threat of a striking serpent, the first G7A concussion torpedo, loaded with eight hundred pounds of explosive, left its forward tube. Powered by compressed air, it left a thin trail of silvery bubbles on its course toward the freighter's stern. It moved with a fluid grace, a smaller replica of the huge machine that had borne it across six thousand miles of ocean. Gradually it rose to within ten feet of the surface and hurtled onward toward its rendezvous.

When the torpedo slammed into the freighter's screws, it ripped open a gash below the waterline with an explosion that lit the sea with fire and fury. There was a long scream of iron as ton after ton of sea broke open the freighter's stern plates. Then there came a second explosion, hotter and redder than the first, sending up a gout of heavy black smoke through which burning men leaped over the shattered deck railing for the sea. Flame spread along the lower deck, greedily chewing its way toward the wheelhouse. A third explosion; a spray of metal and timbers tossed into the sky. Shuddering, the freighter veered toward the beacon light less than a mile away. The captain did not fully realize what had happened. He was perhaps thinking that they had struck something underwater: a reefhead, a sunken wreck. He did not know the screws were mangled and useless or that the fires were already out of control; he did not know the great shafts of the diesel engines had been thrown forward by the blast, grinding men to bloody pulps before them.

When the second torpedo hit, just to starboard of the first strike, the explosion collapsed the stern section of the lower deck. Supports shattered and fell away, and men struggling blindly through smoke and flame were crushed beneath tons of iron. The entire superstructure trembled and began to cave in.

Bulkheads moaned, split, burst as the sea gnawed its way through; iron crumpled like waxed paper; men clawed at each other as they sank, drowning. Some, above decks, were quickly burned into stiffened crisps. The dying ship, filled with the hideous racket of screams and moans, of shattering timber and glass, lurched sharply to starboard and began to sink rapidly at the stern.

A red emergency flare was fired from the remains of the burning wheelhouse; it exploded in the sky with a sharp crack and floated lazily back down toward the sea. Black smoke churned over the freighter, becoming thicker and thicker, filling the air with the stench of scorched iron and burned flesh, until finally it turned the moon ebon.

The surface of the sea began to part beyond the freighter's fiery shape. A rush of swirling white foam marked the ascent of the hunter. Its periscope tower broke the surface, then the rectangular shape of the conning tower appeared, and finally its superstructure, which gleamed as the sea ran off it in red-reflecting streams. The U-boat began to move nearer its victim, its bow slicing cleanly through a carnage of bodies and timber, crates, pieces of railing, ship's furniture. Here a man holding a bleeding comrade and calling out for help, here another in a blackened life jacket, raising up the bloody stumps that had been his arms. A sheen of oil had spread across the sea from the freighter's ruptured tanks, and it too was afire. Flames reflected off the iron hull of the U-boat, burned in the eyes of the men who watched from the conning tower's bridge, glowed in the submarine commander's wolflike eyes.

"Ja. A good hit," he said over the noises of the explosions. It had been ten minutes since the second torpedo left its tube. The freighter was doomed. "Die," he said very softly to the floating blanket of debris and the mass of the sinking ship. "Die."

The black smoke, carrying the scent of death with it, drifted around the U-boat in heavy swirls. Through it the commander could hear a final, long shriek as the freighter headed for the bottom. This was deep water, a thousand feet or more, a trench surrounded by steeply sloping coral reef and sand walls. He cocked his head, listening to a loud gurgling and bubbling of water, the hissing of steam, the half-crazed outcries of drowning men. This was a symphony to him, the almost overpowering music of destruction. He narrowed his eyes and moved his gaze to an object floating off the port bow. It was a life preserver. "All slow," he said, speaking into the voice tube that relayed his orders to the control room. The ring would bear the freighter's name and possibly the registry number; he was fastidious about keeping his leather-bound war diary accurate. "Schiller," he said to the lean blond man who stood nearest him. "You and Drexil get that ring for me."

The two crewmen clambered down the conning-tower ladder to the deck and began to move forward, careful of their footing on the slippery, algae-slimed wood.

The U-boat's bow pushed through a mass of blazing wreckage. Somewhere a man was calling out for God, over and over again; the voice died away abruptly, as if the man's throat had filled with water. Hanging on to the port-deck railing, the oily, littered sea washing around their ankles, the two sailors waited, watching the preserver carried toward them by the waves. Three more of the choppy swells and it would be close enough to grasp by hand. The commander watched, hands folded before him, as Drexil, with Schiller holding his legs, reached over to get it.

And then there was a high, piercing noise that made the commander whirl around. His eyes widened. The noise, coming from the midst of the black smoke, rose until it became a metallic shriek. From the open tower hatch the exec's black-bearded face emerged, his mouth a silent O. At once the commander understood. A battle-station siren. A subchaser, coming up fast on their stern. He roared into the voice tube, "CRASH DIVE! CRASH DIVE!" even as the U-boat's alarm bells shrilled below. Then a second shrieking siren: a second subchaser joining the first. Both of them roaring full-speed, bearing down on the U-boat. The exec dropped through the hatchway, and the commander peered anxiously out across the bulwark. His sailors had the preserver and were frantically making their way through the deepening black troughs.

A bright circular light hit the sea just across the U-boat's bow, and now the sea vibrated with the noise of the subchasers' engines. With a muffled thud a geyser of water rose up to starboard of the conning tower, followed by an explosion that almost tore through the eardrums. The sea heaved around them.

The commander looked into the spotlight, his eyes aching from its brightness, his teeth clenched. Schiller and Drexil would not make the bridge in time. Without a second glance, he threw himself into the yawning hatch and sealed the lid shut over his head.

Like a huge reptilian beast, the great gleaming U-boat slid without hesitation into the depths. The two sailors, floundering in rising water, felt iron and wood drop away beneath their feet. They clutched at a railing, screaming out, focused in the eye of the light.

"THE RING!" Schiller shouted to his mate. "HOLD ON TO IT!"

But then a churn of white water tore it from Drexil's grasp, and it skittered away into the flames. Schiller opened his mouth to cry out, seeing the conning tower sink away, passing him like a descending monster's fin, but salt water streamed into his throat and he almost choked. He kicked forward, trying to grasp hold of the periscope tower, but as he did his leg slammed against something, and he felt himself being pulled down. He jerked at the leg, jerked again; it was useless. Something had caught his ankle and was pulling him after the boat. The sea blinded him, closing over his head. Get free! he heard himself shriek. Get free! The currents enveloped him, carrying him down. He cried out, air bursting from between his teeth, and wrenched at the leg. It came free at last, but there was a sharp cracking noise and pain almost overcame him. He fought his way to the surface. Stroke! the mind commanded the failing body. Stroke!

Schiller found himself amidst a maelstrom of noise and foaming sea. The sky was filled with the smell of cordite and the spinning red and green comets of flares. Shells were dropping all around him, hammering at his brain, and through the nightmare he grasped on to an empty crate and wrapped both arms around it.

When Schiller cleared his eyes he saw Drexil's head bobbing only a few yards away. He cried out, "DREXIL! HOLD ON!" and began swimming, his leg a useless appendage. In another moment he realized he was weak and growing weaker, that he could not tread water, and land was too distant. There was something stringy, like dark clumps of jellyfish, in the waves. Gouts of blood. Intestines. Brains. Bodies torn to pieces. The offal of war. He reached Drexil and it was only when he took the man's shoulder that he realized this man had black hair, and Drexil's had been red.

The corpse, floating in a tattered life jacket, had no face.

White teeth grinned from a pulp of tissues and membranes and nerve fibers. Schiller shouted hysterically and pulled his hands back as if they had been contaminated. He began swimming into the green-glowing ocean, the fires still burning around him, but he was swimming without direction. Ahead was a solid plain of flame, and in the midst of the flame he could see the blackened, shriveled corpses, whirling around and around as if they were spinning above a gigantic whirlpool. He could feel the power of the water over the freighter wrenching at him. He tried to move away from it, but the sea had him and was pulling him down, and he couldn't swim anymore. He wondered where Drexil was and if there were a true peace in death. He lowered his head and opened his mouth to fill his lungs before he went down.

Hands grasped him. Pulled him up from the surface. Threw him down into the bottom of a boat. Men standing over him, peering down.

Schiller blinked, could not make out their faces, could not move his body.

"A live one," someone said, in English.