‘Yes, this is definitely the vehicle that was driven into the field at Foxlow. The tread pattern is an exact fit with the impressions we lifted. We matched soil from the tyres and the wheel arches. Luckily, the interior escaped the worst effects of the fire, and we found traces of gunshot residue on the seat covers. The fabric retains barium and antimony residue better than human skin.’

‘Well, that’s a positive development,’ said Hitchens. ‘We’ve got a definite lead at last.’

‘There’s more,’ said Abbott. ‘I didn’t expect this, but we got some prints off the underside of the dashboard, where it hadn’t been burned too badly. They’re in the system, too. Somebody’s been in this car who has previous form.’

Hitchens took the print-out. ‘Brilliant.’

Fry leaned closer to look. ‘Anyone we know?’

‘The name means nothing to me. Anthony Donnelly, aged thirty-seven, with an address in Swanwick.’

‘Never heard of him.’

‘He has several past convictions for theft from a vehicle and taking without consent, plus all the usual extras – no insurance, driving while disqualified, et cetera, et cetera.’

‘Just an average car thief,’ said Fry, feeling unreasonably disappointed.

‘Mmm, maybe. The most recent charge on his record was in connection with an organized lorry-jacking scheme. Truckloads of white goods diverted to new owners via a lay-by on the A1. I remember that case – five or six people went down for it. But it seems Donnelly was acquitted.’

‘So it could be that he’s gradually moving up in the world, getting involved with more serious operators.’

‘Driver for a professional hit man?’ said Hitchens. ‘Well, let’s go and ask him, Diane.’

‘If that information is from the PNC, then the first thing we have to hope for is that the address is accurate for once.’

The wheels and cables were still humming and rattling, but it no longer seemed to be merely the whir of machinery, the hiss of high-tension steel passing through the air. The noises formed words, murmuring and whispering, mumbling and chattering.

And then John Lowther looked down into the valley again. The fragile crystal of his mind had cracked. He could see the fragments lying on the ground, fading and turning brown, as if they were mere ordinary clay. Through the fracture in his consciousness, he heard the final voice. It was still faint, but he recognized it. Oh, he recognized it all right. In the past, this voice had forced him to do things that he had never wanted to do. And now the voice was back. He had no idea what it would make him do next.

‘Johnny, you know what you have to do.’

They would come for him soon. They would scent him out, sniffing the fear in his sweat. They would use dogs to listen for his voices when they became too loud. And they’d follow him when he left the house, track his movements wherever he went. And one day the searchlights would catch him on the corner of a street, and the lights would probe deep into his mind and see what was there. And the whole world would know his evil.

Cooper could see John Lowther on the platform at the top of the stone tower, leaning over the parapet. Even from this distance, he could tell that Lowther was trembling violently, as if he was no more than a leaf shaken by the wind blowing across the hillside. Strands of hair fell over his forehead, and his eyes were fixed on the horizon. He might have been listening for some distant call that would summon him away, an echo that would reach him from far in the south.

Lowther seemed completely oblivious to the knot of people beginning to cluster round the base of the tower. Their heads were tilted back to stare up at his silhouette, black against the sky. But not once did Lowther look down at the ground.

‘He’s been up there for some time now,’ said the staff member. ‘A visitor started to get uneasy about him. She said he was behaving oddly.’

‘All right. Thank you.’

‘Is there anything else I can do?’

Cooper looked at the concrete apron the tower stood on, and the rough boulders built into the base. ‘Right now, you could help us most by keeping everyone clear of the tower. Well clear – back as far as the play area.’

The man followed Cooper’s gaze, and turned pale. ‘You don’t think he might …?’

But Cooper put a hand on his shoulder. ‘If you could just move these people back, sir.’

‘Of course.’

Georgi Kotsev was examining the doorway to the tower. It was arched, like the entrance to a church, but so narrow that Kotsev looked as though he’d hardly be able to squeeze through it. Signs either side of the doorway warned visitors to take care on the steps. And they gave the building’s name – the Victoria Prospect Tower. Right now, it seemed ironic. Cooper wasn’t looking forward to the prospect at the top.

‘A tricky location,’ said Kotsev.

‘It couldn’t be worse.’

As he’d approached the tower, Cooper had called Control to report the situation. Help would be on the way, and it looked as though he might need it. But it would take time.

When Cooper looked up at the parapet again, a fine mist fell on his face and trickled into his collar. Lowther must be getting cold and uncomfortable up there by now. He wasn’t even dressed for the rain.

‘OK, let’s go and talk to him.’

Rain had blown in through the doorway, creating a dark patch in the stairwell. Inside, the view upwards was dizzying. Stone steps curled away into the tower, with bare tree trunks zigzagging overhead from wall to wall. Cooper could see both the outer and inner surfaces of the staircase at once, which seemed entirely wrong. His instincts were telling him that it was impossible to walk on stairs that coiled so tightly and rose so steeply.

Standing close to the wall, Cooper took hold of the handrail and began to ascend. Mounting the spiral staircase was like walking up a twisted ribbon, or climbing a strand of DNA. It was a sort of stone helix, cold to the touch and smelling of earth. You had to be careful on these steps, or you could fall right through the spiral and plummet to the base of the tower.

Just before the last turn, the bulkhead lights on the wall ended, and Cooper stopped when he saw daylight from the platform. He jumped when he became aware of Kotsev’s breathing below and behind him on the steps. His mind had been so distracted that he’d forgotten his companion.

‘Georgi, you’d better stay back out of sight. We don’t want to frighten him too much.’

‘Dobre. I’ll be right here, behind you.’

Cooper’s heart was beating harder after his climb. All the way up the tower, he’d been conscious of the narrowness of the steps, and the drop through the spiral. One slip could be disastrous.

Slowly now, he eased himself the last few feet on to the platform, trying not to make any sudden noises. Leaving the stairwell was like emerging into a different world, with light and air and an awareness of the valley all around him – banks of trees whispering in the breeze, the cables hissing as they pulled another string of swaying cars across the river. Lowther was standing nearby, his hands resting on the parapet.

‘Mr Lowther, do you remember me? Detective Constable Cooper.’

Lowther seemed to become aware of him for the first time. He tried to back away, but he was already pressed hard against the parapet and could only scrape slowly around the platform until he was on the eastern side. He stood with the Heights of Abraham behind him, birds swooping through the woods, water dripping from branch to branch, cable cars descending to the base station.

Cooper took a step backwards, trying to judge a safe distance that wouldn’t make Lowther feel under too much pressure. At the same time, he had to find some way to keep the man’s attention on him. At the moment, his concentration seemed to be wandering, his eyes darting around the landscape, distracted by the whir of cables and the voices of people on the ground below.