During the next two weeks, as the southern horizon became increasingly darkened by the approaching rain-clouds, Kerans saw Strangman frequently. Usually he would be driving his hydroplane at speed around the lagoons, his white lounge suit exchanged for overalls and helmet, supervising the work of the salvage teams. One scow, with six men, was working in each of the three lagoons, the divers methodically exploring the sunken buildings. Occasionally the placid routines of descent and pump would be interrupted by the sounds of rifle fire as an alligator venturing too near the divers was despatched.

Sitting in the darkness in his hotel suite, Kerans was far away from the lagoon, content to let Strangman dive for his loot as long as he would soon leave. More and more the dreams had begun to encroach on his waking life, his conscious mind becoming increasingly drained and withdrawn. The single plane of time on which Strangman and his men existed seemed so transparent as to have a negligible claim to reality. Now and then, when Strangman came to call on him, he would emerge for a few minutes on to this tenuous plane, but the real centre of his consciousness was elsewhere.

Curiously, after his initial irritation, Strangman had developed a sneaking liking for Kerans. The biologist's quiet, angular mind was a perfect target for Strangman's dry humour. At times he would subtly mimic Kerans, earnestly taking his arm during one of their dialogues and saying in a pious voice: "You know, Kerans, leaving the sea two hundred million years ago may have been a deep trauma from which we've never recovered…"

On another occasion he sent two of his men over in a skiff to the lagoon; on one of the largest buildings on the opposite bank they painted in letters thirty feet high: TIME ZONE Kerans took this banter in good part, ignoring it when the divers' lack of success made it more severe. Sinking backwards through the past, he waited patiently for the coming of the rain.

It was after the diving party arranged by Strangman that Kerans first realised the true nature of his fear of the man.

Ostensibly the party had been devised by Strangman as a social function to bring the three exiles together. In his laconic, off-hand way Strangman had begun to lay siege to Beatrice, deliberately cultivating Kerans as a means of securing an easy entree to her apartment. When he discovered that the members of the trio rarely saw each other he evidently decided on an alternative approach, bribing Kerans and Bodkin with the promise of his well-stocked cuisine and cellar. Beatrice, however, always refused these invitations to luncheon and midnight breakfast-Strangman and his entourage of alligators and one-eyed mulattos still frightened her-and the parties were invariably cancelled.

But the real reason for his 'diving gala' was more practical. For some time he had noticed Bodkin punting around the creeks of the former university quarter-often the old man, much to his amusement, would be trailed around the narrow canals by one of the dragon-eyed scows, manned by the Admiral or Big Caesar and camouflaged with fern fronds, like a lost carnival float-and attributing his own motives to others, assumed that Bodkin was searching for some long-buried treasure. The focus of his suspicions finally became fixed on the submerged planetarium, the one underwater building to which there was easy access. Strangman posted a permanent guard over the little lake, some two hundred yards to the south of the central lagoon, which contained the planetarium, but when Bodkin failed to appear at the dead of night in flippers and aqualung Strangman lost patience and decided to anticipate him.

"We'll pick you up at seven tomorrow morning," he told Kerans. " Champagne cocktails, cold buffet, we'll really find out what old Bodkin has got hidden down there."

"I can tell you, Strangman. Just his lost memories. They're worth all the treasure in the world to him."

But Strangman had let out a peal of sceptical laughter, roared away in the hydroplane and left Kerans hanging helplessly to the switchbacldng jetty.

Promptly at seven the next morning the Admiral had come for him. They collected Beatrice and Dr. Bodkin and then repaired to the depot ship, where Strangman was completing his preparations for the dive. A second scow was filled with diving equipment-both aqualung and suit-pumps and a telephone. A diving cage hung from the davit, but Strangman assured them that the lake was free of iguanas and alligators and there was no need to remain in the cage underwater.

Kerans was sceptical of this, but for once Strangman was as good as his word. The lake had been cleared completely. Heavy steel grilles had been lowered into the water at the submerged entrances, and armed guards sat with harpoons and shotguns astride the booms. As they entered the lake and moored against a shaded waterside balcony on the eastern side the last of a series of grenades was being tossed into the water, the sharp pulsing explosions spewing up a flotsam of stunned eels, shrimp and somasteroids, which were promptly raked away to one side.

The cauldron of submerged foam dispersed and cleared, and from their seats by the rail they looked down at the wide domed roof of the planetarium, wreathed in strands of fucus, as Bodkin had said like a giant shell-palace from a childhood fairy tale. The circular fan light at the apex of the dome was covered by a retractable metal screen, and an attempt had been made to lift one of the sections, but to Strangman's chagrin they had long since rusted into place. The main entrance of the dome was at the original street level, too far down to be visible, but a preliminary reconnaissance had revealed that they would be able to enter without difficulty.

As the sunlight rose across the water Kerans gazed down into the green translucent depths, at the warm amnionic jelly through which he swam in his dreams. He remembered that despite its universal superabundance he had not fully immersed himself in the sea for ten years, and mentally recapitulated the motions of the slow breaststroke that carried him through the water while he slept.

Three feet below the surface a small albino python swam past, searching for a way out of the enclosure. Watching its strong head swerve and dart as it evaded the harpoons, Kerans felt a momentary reluctance to entrust himself to the deep water. On the other side of the lake, behind one of the steel grilles, a large estuarine crocodile was wrestling with a group of sailors trying to drive it off. Big Caesar, his great legs clamped to the narrow sill of the boom, kicked savagely at the amphibian, which snapped and lunged at the spears and boathooks. Over thirty feet long, it was well over ninety years old, and measured six or seven feet in chest diameter. Its snowwhite under-belly reminded Kerans that he had seen a curiously large number of albino snakes and lizards since Strangman's arrival, appearing from the jungle as if attracted by his presence. There had even been a few albino iguanas. One had sat on his jetty the previous morning, watching him like an alabaster lizard, and he had automatically assumed that it bore a message from Strangman.

Kerans looked up at Strangman, who stood in his white suit in the bows of the vessel, watching expectantly as the crocodile thrashed and slammed against the grille, almost toppling the giant negro into the water. Strangman's sympathies were all too obviously with the crocodile, but not for any reasons of sportsmanship or from a sadistic desire to see one of his principal lieutenants gored and killed.

Finally, amid a confusion of shouts and curses, a shotgun was passed to Big Caesar, who steadied himself and discharged both barrels into the hapless crocodile below his feet. With a bellow of pain, it backed away into the shallows, its tail smacking the water.

Beatrice and Kerans looked away, waiting for the coup de grace to be administered, and Strangman swarmed along the rail in front of them, eager for a better vantage point.

"When they're trapped or dying they smack the water as an alarm signal to each other." He put a forefinger on Beatrice's cheek, as if trying to make her face the spectacle. "Don't look so disgusted. Kerans! Damn it, show more sympathy for the beast. They've existed for a hundred million years, they're among the oldest creatures on the planet."

After the animal had been dispatched he still stood elatedly by the rail, bouncing on the balls of his feet, as if hoping that it would resuscitate itself and make a come-back. Only when the decapitated head was hoisted away on the end of a boathook did he turn with a spasm of irritation to the business of the dive.

Under the supervision of the Admiral, two of the crew made a preliminary dive in aqualungs. They climbed down the metal ladder into the water and glided away towards the sloping curve of the dome. They examined the fanlight, then tested the semicircular ribs of the building, pulling themselves across the dome by the cracks in the surface. After their return a third sailor descended, with suit and line. He clumped slowly across the cloudy floor of the street below, the thin light reflected off his helmet and shoulders. As the lines wound out, he entered the main doorway and disappeared from view, communicating by telephone with the Admiral, who sang out his commentary for all to hear in a rich fruity baritone. "in de pay-box… now in de main lounge… Jomo says de seats in de church, Captain Strang', but de altar gone."

Everyone was leaning over the rail, waiting for Jomo to reappear, but Strangman was slumped back moodily in his chair, face clamped in one hand.

"Church!" he snorted derisively. "God! Send someone else down. Jomo's a bloody fool."

"Yes, Captain."

More divers descended, and the first champagne cocktails were brought round by the steward. Intending to dive himself, Kerans sipped lightly at the heady effervescence.

Beatrice touched his elbow, her face watchful. "Are you going down, Robert?"

Kerans smiled. "To the basement, Bea. Don't worry, I'll use the big suit, it's perfectly safe."

"I wasn't thinking of that." She looked up at the expanding ellipse of the sun just visible over the rooftop behind them. The olive-green light refracted through the heavy fern fronds filled the lake with a yellow, swampy miasma, drifting over the surface like vapour off a vat. A few moments earlier the water had seemed cool and inviting, but now had become a closed world, the barrier of the surface like a plane between two dimensions. The diving cage was swung out and lowered into the water, its red bars blurred and shimmering, so that the entire structure was completely distorted. Even the men swimming below the surface were transformed by the water, their bodies as they swerved and pivoted turned into gleaming chimaeras, like exploding pulses of ideation in a neuronic jungle.