Fry was relieved when DI Hitchens called her out of the room. She was exhausted, and her head was aching again, worse than ever. Though she’d managed to get home some time in the early hours of the morning, she hadn’t slept at all. Whenever she’d started to drift out of consciousness, those steel springs had snapped in her forehead and plunged deep into the nerves behind her eyes, like the teeth of a gin trap.

‘Billy McGowan is changing his story,’ said Hitchens.

‘Really?’

‘It looks as though he’d decided that Richard Slack was the perfect scapegoat. Being dead can make you useful sometimes.’

Fry nodded. ‘McGowan used to work for Abraham, didn’t he? Was he protecting the old man?’

‘No,’ said Hitchens. ‘Vernon.’

‘But Professor Robertson –?’

‘The team at Robertson’s house found comprehensive records on the professor’s computer. It turns out that Vernon Slack was one of his private students. Perhaps Vernon thought he had something to prove to the people who thought he was so useless.’

‘A funny way of doing it, sir.’

Hitchens shrugged. ‘I don’t know. A special insight into the death business? Maybe he intended to defy expectations and take over Hudson and Slack one day. He could have been planning to take the firm in a different direction.’

Fry squinted uneasily at the DI, but realized he was joking.

‘He was Richard Slack’s son,’ she said. ‘He could have inherited his father’s ruthless business streak, but it got twisted somewhere along the way. And instead, everyone ended up feeling sorry for him.’

‘Everyone, Diane?’

‘Well, Billy McGowan must have felt some sympathy for him. If someone like McGowan was willing to keep quiet about Vernon’s arrangement with Professor Robertson, then Vernon must have had something about him that I couldn’t see.’

‘I suppose so.’

Fry looked at the door of the interview room. ‘That still doesn’t explain why the old man killed him. Why did he do that?’

On the other side of the door, Abraham Slack sat looking at the triple-deck tape machine with a dead stare, devoid of emotion. Even the tapes had ceased to record his silence.

Ben Cooper was in the kitchen of Greenshaw Lodge when Fry found him later that day. He’d been watching the house gradually become sparser and more empty as the forensic team carried away items for examination. In the sitting-room display cabinet, he could still see the photograph of Abraham Slack and his family, though the SOCOs’ lights reflecting off the glass made the individual figures impossible to identify.

‘There was something about the way Vernon spoke,’ he said, when Fry negotiated the safe path to reach him. Cooper was trying to get his thoughts clear in his own mind, and Fry was the only person he thought might understand.

‘Shouldn’t you still be in hospital?’ she said.

‘They’ve stitched me up and given me a tetanus jab. There was no point in staying there any longer.’

She looked at his bandaged foot. ‘No bones broken or anything? I’ve seen such horrible stories about animal traps.’