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.’