He could sense the turbulence in the water, waves rippling down. When he looked up there was the weird, incandescent glow of the spot-lamp on the other scooter as it passed overhead. He waited for a moment or two, then went up slowly.

At twenty feet he leveled out, switched on the motor, but not the spot, and went after the other scooter. Only in patches was visibility really bad and at this depth the moonlight streamed in through fissures in the rock like regularly spaced lamps along a dark road.

When he emerged at last from the great central nave into clear water he switched off the aquamobile and surfaced.

Raoul Guyon sat in the stern of the dinghy. A yard or two away the frogman stood waist-deep in water on the shelving reef beside his scooter, a loaded spear-gun in his hands. It was almost as if they were holding a conversation.

Mallory released his grip on the aquamobile, went under the surface and swam forward. He erupted in a surge of power, slid his right arm about the man’s neck and fell backwards, towing him into deep water, tearing the air-hose from his mouth.

They sank down through the clear water, the spear-gun spiralling off to one side. Mallory wrenched again with his free hand, pulling away the mask, and the man’s face turned up, contorted with fear.

Mallory hung on, even when a clutching hand reached backwards, wrenching away his own air-hose. He compressed his lips and tightened his grip. Blood began to seep from the man’s nostrils in two clouds and a moment later he swung loosely against Mallory’s arm. Mallory unlocked his fingers and the body bounced away, spun round twice and started to sink.

There was a roaring in his ears and his temples pounded. He kicked for the surface and bumped against the side of the dinghy, gasping and choking for breath. Guyon reached over and grasped his outstretched hand and Mallory stumbled up the sloping shelf of rock and crouched on his hands and knees, chest heaving.

Guyon jumped knee-deep into the water beside him and helped him up, pulling away the mask, his face strained and anxious in the moonlight. When he spoke his voice sounded faint and far away and Mallory shook his head several times.

The roaring subsided abruptly and he gasped: “No time for questions. I ran into a little trouble. We’d better get moving.”

“You found L’Alouette!”

“She’s there, all right. Moored to the jetty under the island just like we thought. Room for a couple more from the look of the place.”

He unbuckled the heavy aqualung, swung it into the prow and clambered aboard the dinghy. As he started the outboard motor Guyon unhooked the painter and followed him. A second later and the dinghy was moving back towards lie de Roc, following the twisting channel between the great rocks which already reared up on either side as the tide turned.

“What happens now?” Guyon said.

“We call up Leviathan the moment we get back. Those motor torpedo boats from St. Helier will be here before you know it.”

The dinghy rocked in the turbulence as it swept on a fast current between high black walls and turned towards the point. Behind them a full-throated roar shattered the night and Guyon raised the night-glasses and looked back. When he took them down his face looked very white in the moonlight.

“It’s that damned speedboat of de Beaumont’s. Coming up fast on this side of the reef. Must be doing all of fifteen knots.”

Mallory glanced back, catching a brief glimpse of the thin pencil of light that was the speedboat’s spot, and opened the throttle of the dinghy’s outboard motor. The strong current was running against them now as they tried to breast the point, and the light craft was twisted round, a wave splashing across her prow.

“Throw the aqualung overboard,” Mallory shouted.

Guyon scrambled to his knees, reached for the straps, heaved and slid the aqualung over. There was an immediate difference, the prow riding over the next wave, and they turned the point and moved into what should have been calmer water.

The turning tide at this point clashed headlong with the usual strong coastal current, and all around them great patches of white water joined with others, sending irregular waves cascading against the cliffs, the undertow sucking them out again.

The dinghy wallowed in the trough between two great swells, her speed cut in half, and, behind, the roar of the speedboat drew inexorably nearer.

“We’ll never make it to the harbour,” Guyon called. “A couple more minutes and they’ll see us.”

A great heaving swell was building up to starboard. As it swept in, lifting the dinghy high into the air, Mallory caught a glimpse of Hamish Grant’s house tucked into a fold at the top of the cliffs, a light shining in one of the ground-floor rooms. He swung the tiller over and the current drove the dinghy in towards the cliffs at tremendous speed.

The gap in the inlet had been at least twenty yards across, but the real problem was that line of jagged rocks blocking the entrance as surely as if it had been a steel portcullis. The one slim hope was that the waves, sweeping in, would raise the water-level and carry them over.

He shouted to Guyon: “This is going to be rough. Hang on and get ready to swim.”

The Frenchman looked back once, his lips moving in reply, but the roaring of the sea drowned his words. Mallory held on to the tiller with both hands. Strange, swirling currents twisted them round and the dinghy was carried helplessly in.

The opening of the cove appeared suddenly in the face of the cliff, water boiling through in a great surge. At one side white spray foamed high in the air, while, all around, dirty cream patches formed as rocks showed through.

The dinghy slewed broadside into the entrance, lifted high and smashed down upon a great green slab of rock. The tiller was wrenched from Mallory’s hand and the outboard motor was torn away with a section of the stern.

The dinghy slithered forward across the reef and ground to a halt, a jagged edge of rock smashing through the hull. Guyon went head first over the prow with a cry and Mallory went after him.

The Frenchman tried to stand and Mallory plunged through the boiling surf, hands outstretched to meet him. For a moment they clung together and then another wave, cascading in across the reef, bowled them over.

Guyon went under, and Mallory, striking after him, found himself in deep water. He grabbed the Frenchman by the collar of his jacket and struck out, the current pushing them forward. His feet touched sand and he stood up, pulling Guyon after him. Water boiled waist-high again, tugging at their limbs. As it receded they lurched forward, feet slipping in the shingle, and staggered up the narrow strip of beach at the base of the cliffs.

Someone was playing the piano, an old, pre-war Cole Porter number with something of the night in it, something of warmth and love and hope that seemed to belong to another age than this.

Crouching in the bushes below the terrace, Mallory was caught for a brief moment, unable to go forward or back. Guyon groaned beside him, coughing up water, and Mallory pulled him to his feet and they staggered up the steps.

The French window was ajar, one end of a red velvet curtain billowing out as a gust of wind lifted it. He took a deep breath and opened it wide.

The fire burned brightly on the stone hearth and Hamish Grant’s hair gleamed like silver in the lamplight as he leaned in his wing-backed chair, smoking a cheroot. Anne sat opposite, staring into the fire while Fiona played the piano.

It was Fiona who saw them first. She gave a sudden gasp, her hands striking a false chord, and jumped to her feet. Anne stood up slowly and Hamish Grant turned his head and looked directly at the window.

“Sorry about this,” Mallory said as he moved forward, one arm still around Guymon’s shoulders.