Of course. Halloween. The time when the forces of evil were at their most powerful, the night when the doors to the underworld stood open and it was possible to communicate with the dead. Another belief that died hard, despite the efforts to make it all about pumpkins and apple bobbing.

‘I can’t be alive by then,’ said Lowther. ‘I can’t.’

‘All we need to do,’ said Cooper, ‘is get you down from here and take you to see a doctor. They can stop the voices, John. You know they can. They’ve done it before.’

‘You don’t understand,’ said Lowther, shaking with agitation. ‘Mum said you understood, but you don’t. When people talk to me now it’s like a different kind of language. It’s too much to hold in my mind at once. My head is overloaded and I can’t understand what they say. It makes me forget what I’ve just heard because I can’t hear it for long enough. It’s all in different bits, you see, which I have to put together again in my head. Until I do that, it’s all words in the air. I have to try to figure it out from people’s faces. But their faces always say something different from their voices.’

‘Mr Lowther, please calm down and stop talking for a minute.’

‘I have to keep talking, to drown out the voices.’

‘We’ll get you some treatment, to make the voices go away.’

‘They’ll never go away – not completely. They’ll always be there . . .’ He seemed to be listening to something. Whatever he heard terrified him, and he shouted the next few words. ‘It’s Lindsay’s voice. Lindsay – and the children. I heard them scream. I’ll always hear them scream.’

‘Look –’

What happened next, Cooper wasn’t quite sure. He’d been trying to concentrate on what John Lowther was saying, so he could respond and reestablish a connection. He’d been trying to maintain eye contact, to hold the man’s attention and keep him talking. But something had spooked him. Lowther jerked backwards against the parapet as if he’d been shoved in the chest or pulled back by an invisible hand.

Then he was going over, and Cooper was diving forward to grab hold of him. He found only clothes to clutch at, smooth material that slipped through his fingers and left him nothing to grip. He felt Lowther’s weight shifting inexorably outwards as gravity seized him and dragged him over the edge.

‘Georgi! Help me, quick!’

Kotsev came thumping up the steps, gasping as he reached the top.

‘Dyavol da go vzeme! Oh hell!’