By morning, crime scene tents had sprung up like mushrooms in the autumn rain. SOCOs, photographers and police officers were finding different ways of getting lost while travelling from the old engine house at Greenshaw Lodge to the ruins of Fox House Farm on the Alder Hall estate.

As a result, the forensic work went slowly, and it was well into the day before the bodies of Professor Freddy Robertson and Vernon Slack were removed. Longer still before recovery work began on the skeletal remains from the abandoned building.

Meanwhile, Abraham Slack wasn’t talking. In the interview rooms at West Street, detectives were used to frustrating silences. But the old man, sitting with his solicitor, refused to offer even the beginnings of an explanation for his decision to kill his grandson. The first discharge of the shotgun had torn apart Vernon’s torso, and pellets from the second barrel had shredded both his lungs, so he’d died breathing his own blood.

As he listened to Diane Fry reading the description of Vernon’s injuries, Slack hung his head and sagged with distress. The interview had to be suspended while a doctor examined him. To Fry, the old man looked as though he’d given up at that point. Perhaps he had. But when they got him back into the interview room, he still wasn’t talking.

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?’