She was less than a hundred yards away now and he allowed himself the brief, intoxicating thought of choice. He could change things, right now, at the last moment. He could allow her to live. He felt the authority in that choice, the ultimate level of control. In this instant, he wielded the power of life and death and the thought electrified him.

Fifty yards to go. He noticed that she was wearing earphones, the thin wire dancing loosely as it ran down to her pocket . . .

Twenty yards. Satisfied that she would pass on his right, he lowered his head, muscles taut, as she drew level . . .

. . . and he exploded, swinging the stone fiercely up into her stomach, lending all his might to the blow that smashed the air from her lungs and bent her over, staggering to her knees.

She had no breath to shout.

Immediately, he was there, bundling her off the path, down a grassy slope towards the beach, moving her as fast and as far as he could before she understood what was happening, before she fought, before she became deadweight.

And then, as she began to panic, he tried to swing the stone round, to connect with the side of her head, to end it quickly, but his gloved fingers lost their purchase and he felt his weapon slip away, thudding into the shingle nearby.

Damnation!

It was too late to stop – he was committed now. As she desperately tried to get air, he allowed his weight to knock her to the ground, dropping onto her to deflate her lungs still further as his hands took hold of her throat.

She made terrible little choking sounds, the worst he had ever heard, and he flinched as her struggling became desperate, turning his head away to avoid her flailing arms.

And to avoid seeing her.

It became unbearable, and he started to feel nausea rising through his adrenalin. Ten seconds . . . fifteen . . . for fuck’s sake! And then, mercifully, she began to fail, the movements becoming intermittent, weaker, until finally she sagged beneath him and was still.

He realised he was shaking.

Taking a deep breath, he forced his fingers to relax, releasing their grip on her. Straightening up, he anxiously glanced back over his shoulder towards the path and the houses beyond, but he was alone. Utterly alone.

And now he began to sense the onset of exhilaration, the terrible rush building inside, but he pushed it away, closed his mind to it.

Not yet.

He scrambled quickly to his feet and looked around, his thoughts racing through the mental checklist that he had prepared for this moment. Gloves and clothing were intact, keys still in his pocket . . . He’d dropped the stone coming down the slope but he’d left nothing else behind.

Move . . .

She was lying in a crumpled heap, terribly exposed on the open beach, but the tall reeds were just a short distance away. Grunting with determination, he grabbed her ankles and started to drag her towards the water. Moving down across the swathe of small stones was quite easy, but it became harder as he went from shingle to mud. He battled on, straining to pull her as his new trainers sank into the grey ooze, but after a final burst of effort he was able to drop to his knees, the body safely nestled between two large clumps of reeds.

After taking a moment to calm his breathing, he rolled her over onto her back, finding her eyes thankfully closed.

He squatted down again, noting that her T-shirt had ridden up as he’d dragged her, exposing her pale stomach and the base of her bra. Gently, he tugged the edge of her T-shirt down to cover her again, to allow her a little dignity. Then he rocked back on his heels, studying her, looking for something small, something that wouldn’t be missed. His eyes settled on her earphones, now a tangled mess after being trailed through the mud. He followed the wire back to her pocket and pulled. Carefully, he revealed the music player she’d been listening to. Deeper in her pocket, he discovered her keys.

Taking them in his hand, he considered for a moment, then reached into his jacket and fished out the white envelope. Opening it, he withdrew a small key, which he placed on her stomach. Disconnecting the earphones, he slid her MP3 player into the envelope, which he stuffed back into his jacket, zipping the pocket shut. Then, hindered by his gloves, he picked up the key and carefully started working it onto her key chain. It took a moment, but finally it was done, and he carefully returned the keys to their place in the pocket of her shorts.

He glanced back up the beach, then lifted her wrist to look at the sports watch that was still clocking up the seconds since she’d started her run: 37 minutes and counting . . . There was no reason to give the police any help with the time of death, so he removed the watch and deliberately smashed it against a nearby rock, repeatedly hitting it until it was in pieces.

For a moment, he gazed down at her, checking to make sure she wasn’t still breathing. Frowning, he crouched beside the body and rolled it over, pressing her face down into the wet mud.

Better to be sure.

When he was satisfied, he reached over to lift the tangled earphones, balling them into a muddy mass and standing up to throw them out into the water. Then, with one final glance down at the body, he picked his way back onto the shingle before turning and walking away along the shore.

The excitement he’d been fighting suddenly welled up inside and now, as he gazed out at the broad, bleak horizon, with its low clouds and distant smokestacks, he finally let it wash over him – a rapture of such sickening intensity that he almost wanted to cry out. The power, the utterly addictive thrill of power, so profound he could scarcely comprehend it. He shook with the cold, dark joy of his own supremacy. There was nothing he couldn’t do.

He saw nobody as he walked back, but the houses were far behind him and the weather was closing in again – it wasn’t a morning for the beach. He found the plastic bag just where he’d left it and, screened by the bushes, he began to strip off his clothes. Everything, from his shoes to his watch, was removed and placed in a second refuse sack before he retrieved his own clothes and started to dress.

Ten minutes later, he was back at the car. From habit, he had double-bagged everything he’d worn on the beach, but in the event he needn’t have worried. There had been no blood, and he hadn’t needed to clean himself up. He placed the bulging refuse sack in the boot and climbed into the car as the first spots of rain began to appear on the windscreen.

Perfect.

He drove cautiously under the railway bridge. Nobody saw him turn left and join the main road, keeping his speed just under the 50 mph limit. He came to the junction – a signpost pointed left to Severn Beach – but he went straight on, following the road inland, passing over the motorway and accelerating as he came to the dual carriageway. In minutes, he had reached the roundabout where he joined the M48, one anonymous car disappearing into the relentless flow of traffic from the Severn Bridge.

It was a little after ten when he arrived back at home. He’d changed the number plates as soon as he left the motorway – emerging from a quiet country lane with his own registration again – but he was tired and in no mood to rush the rest of the clean-up. He had the whole day to dispose of the clothes in one of the charity recycling bins outside the local supermarket, to drop the wristwatch into the river and to stuff the refuse sacks into a lay-by rubbish bin. Right now he wanted sleep.

His eyes had grown heavy, and the mood of elation that normally carried him for days and weeks was already starting to ebb away. He’d started to wonder about it as he’d driven back through Devizes and on along the winding road that led back to Salisbury. Somehow, everything had been just a little too straightforward, had happened just a little too quickly for him. So much of the reward came from the scale of the challenge, but this time? This had been one of the simplest yet. He felt a gnawing sense of dissatisfaction that began to trouble him, but he didn’t want to think about it now.