I left the pool and retraced the Russian's steps to the pumphouse.

The wooden doors had jumped their latch, exposing the electric motor, heater and timing mechanism. The cramped space was filled with sacks of pool-cleaner, the chlorine-based detergent that Monsieur Anvers poured into the loading port. Twice each day the soft powder diffused across the water, forming milky billows that dissolved the faint residues of human fat along the water-line.

I ran my hand over the nearest wax-paper sack. Its industrial seals were unbroken, but a stream of powder poured onto the floor from a narrow tear. Sitting down, my legs stretched out in front of me, I gripped the sack and pulled it onto the cement apron. A second vent, large enough to take a child's index finger, punctured the heavy wrapper, and the cool powder flowed across my knees.

I tore away the paper between the holes, and slid my hand into the sticky grains. They deliquesced as I exposed them to the sunlight, running between my fingers to reveal a bruised silver nugget like a twisted coin. I cleaned away the damp powder, and stared down at the deformed but unmistakable remains of a high-velocity rifle bullet.

I upended the sack and let the powder flow across the apron.

A second bullet lay between my knees, apparently of the same calibre and rifling marks, crushed by its impact with a hard but uneven structure.

I laid the bullets on the ground and reached into the pumphouse, running my hands over the remaining sacks. Their waxed wrappers were unbroken, and the pumping machinery bore no signs of bullet damage. I assumed that the stock of detergent had remained here when the pool motor was switched off after David Greenwood's death. Restarting the motor a few days before our arrival, Monsieur Anvers had decided to leave the punctured sack where it lay.

I turned to the wooden doors, feeling the smoothly painted panels, fresh from a builder's warehouse. The chromium hinges were bright and unscratched, recently reset in the surrounding frame. With my hand I brushed away the loose grains of powder and felt the apron beside the doors. The smooth cement had been faintly scored by a rotating abrader, and the steel bristles had left small whorls in the hard surface, as if carefully erasing a set of stains or scorch-marks.

I felt the bullets between my fingers, guessing that they had not been deformed by their impact with the pine doors or the detergent sack. A larger object, with a bony interior, had absorbed the full force of the bullets. Someone, security guard or hostage, had collapsed against the pumphouse doors, and had then been shot at close range, either by himself or others.

I listened to the cicadas in the Yasudas' garden, and watched the dragonflies flitting around the tennis court. According to Wilder Penrose, the three hostages had been killed inside the garage. I imagined the brief gun-battle that had taken place near the house, as David Greenwood made his final stand against the security guards and gendarmes. He had murdered the hostages in an act of despair, and then sat down against the pumphouse, ready to kill himself, staring for the last time at the skies of the Côte d'Azur as the police marksmen approached.

But no one, holding a rifle to his own chest, a thumb outstretched to the trigger guard, could shoot himself twice. Whoever the victim, an execution had taken place beside the swimming pool of this quiet and elegant house.

A Range Rover of the security force cruised the avenue, and the driver saluted me as he passed. I stood outside the garage, the remote control unit in my hand. The doors rolled noiselessly, and light flooded the interior, a space for three cars with wooden shelves along the rear wall.

For all Penrose's assurance that the garage had been rebuilt, the original structure remained intact. The concrete floor had been laid at least three years earlier, and was slick with engine oil that had dripped from some of the most expensive cars on the Côte d'Azur. Cans of antifreeze stood on the shelves, along with bottles of windscreen fluid and an Opel Diplomat owner's manual.

I carefully searched the floor, and then examined the walls and ceiling for any traces of gunfire. I tried to imagine the hostages trussed together, squinting at the light as Greenwood entered the garage for the last time. But there were no bullet holes, no repairs to the concrete pillars, and no hint that the floor had been cleaned after an execution.

Almost certainly the three men, the luckless chauffeurs and maintenance engineer, had died elsewhere. At least one of them, I suspected, had been shot in the garden, sitting with his back to the doors of the pumphouse.

I closed the garage and rested against the warm roof of the Jaguar. It was a little after six o'clock, and the first traffic was leaving Cannes for the residential suburbs of Grasse and Le Cannet. But Eden-Olympia was silent, as the senior executives and their staffs remained at their workstations. Jane had asked me to collect her from the clinic at 7.30, when the last of her committee meetings would end.

A fine sweat covered my arms and chest as I walked back to the garden, a fear reaction to the garage. I had expected a chamber of horrors, but the ordinariness of the disused space had been more disturbing than any blood-stained execution pit.

I stripped off my shirt and stood by the diving board. Calming myself, I stared down at the dappled floor, a serene and sun-filled realm that existed only in the deeps of swimming pools. A water spider snatched at a drowning fly, and then skied away. As the surface cleared, I saw the bright node of the coin, a gleaming eye that waited for me.

I dived into the pool, broke through the foam and filled my lungs, then turned onto my side and dived again towards the silver pearl.

7 Incident in a Car Park

'They're rifle bullets, steel-capped,' I told Jane in her office at the clinic. 'Probably fired from a military weapon. Two of them were in the pumphouse. The third I fished out of the pool an hour ago.'

Jane watched me as I leaned across her desk and placed the three bullets in her empty ashtray. Stolen from a pub in Notting Hill, the ashtray was a reassuring presence, proof that a small part of Jane's rackety past still survived in this temple of efficiency.

Jane sat calmly in her white coat, dwarfed by a black leather chair contoured like an astronaut's couch. She touched the bullets with a pencil, and raised a hand before I could speak.

'Paul – take it easy.'

Already she was playing the wise daughter, more concerned about my adrenalin-fired nerviness than by the unsettling evidence I had brought. I remembered her under the roadside plane trees near Arles, calmly sucking a peach as the engine steamed and I rigged an emergency fan belt from a pair of her tights.

She prodded the bullets, moving them around the ashtray. 'Are you all right? You should have called me. This Russian – what's Halder playing at?'

'I told him not to worry you. Believe me, I've never felt better. I could easily have run here.'

'That's what bothers me. The Russian didn't hurt you?'

'He brushed my shoulder, and I slipped on the grass.'

'He spoke English?'

'Badly. He said his name was Alexei.'

'That's something.' Jane stood up and walked around the desk.

Her small hands held my face, then smoothed my damp hair. She paused at the swollen bruise above my ear, but said nothing about the wound. 'Why do you think he was Russian?'

'It's a guess. He mentioned someone called Natasha. Do you remember those touts near the taxi ranks at Moscow Airport? They had everything for sale – drugs, whores, diamonds, oil leases, anything except a taxi. There was something seedy about him in a small-time way. Poor diet and flashy dentistry.'