In the sitting room, Fry began to open the drawers of a small dresser, her gloved fingers moving through the contents. Some CDs, spare batteries, a pair of gloves. Luke Irvine was examining a desktop PC on a table in the corner. Was Tarrant the type to send a lot of emails? She doubted it, but you had to check. Just as Cooper came into the room from the kitchen, she touched something solid in the drawer. Her fingers closed around an unusual shape.

‘That’s odd.’

Cooper came over to her. ‘What have you found, Diane?’

‘I’m not sure.’

Fry showed him the object she’d found in the drawer – a small, flared brass and copper tube, no more than nine inches long.

‘Those things aren’t easy to use,’ said Cooper. ‘It takes a lot of practice to get it right.’

‘What is it?’

‘A hunting horn, of course.’

Carefully, Fry bagged the horn for evidence.

‘Adrian Tarrant must have had it,’ she said. ‘So it looks as though the kill call was real, after all – and Tarrant was the one who blew it. For a while, I thought the sabs were making it up.’

‘Rather a theatrical gesture, wasn’t it?’ said Cooper.

‘Theatrical?’ Fry thought of all the gleaming horses and red coats, the panting hounds and glossy boots, all the centuries of ritual and tradition. ‘Well, that’s what it’s all about, isn’t it? A bit of theatre.’

‘The kill call?’ said Irvine, straightening up from the PC when he overheard their conversation.

‘It’s a hunting term,’ explained Cooper. ‘Three long notes, calling the hounds in to kill the fox.’

‘Oh, I see. It has another meaning, too.’

‘Of course. Something to do with computer programming, isn’t it?’

‘Yes, it’s used in multi-tasking. The kill call lets one process terminate another.’

Fry looked around Adrian Tarrant’s home, sniffing at the beer cans and unwashed plates. ‘Well, let’s see if we’ve found enough to terminate Mr Tarrant’s activities.’

THAT AFTERNOON, FRY spent a long time sitting across the table from Adrian Tarrant in an interview room, watching him as if he was an animal at the zoo. She wasn’t sure what sort of animal he would be. He might as well have been a hibernating bear, for all the communication that was going on between them.

Tarrant was silent, stubbornly so. He didn’t even need the presence of the duty solicitor to encourage him to go ‘no comment’. But now and then he raised his head and stared back at her. Fry remembered his eyes – those eyes that had stared at her as he ran past her near Birchlow on Tuesday, and again in the woods on Saturday.

‘Why did you kill Patrick Rawson?’ she asked. ‘Was it for money? We know you lost your job. Or perhaps you’ve got yourself into some kind of trouble? Do you owe a lot of cash? Is it for drugs?’