Fry sighed. ‘Time of death is estimated at between nine and nine thirty this morning. We won’t get a confirmed cause of death until after the postmortem, of course, but it looked like blunt-force trauma to me. There were certainly serious head injuries.’

‘Good. But if you’re considering suspicious circumstances, do you have any suggestion of a motive?’

‘Not until we’ve gone into the victim’s background thoroughly. We don’t know yet what he was doing in Derbyshire, even. That should give us a line of enquiry.’

‘An arranged meeting?’

‘That’s what I’m hoping,’ said Fry. ‘The old agricultural research station is too unusual a place for a random encounter with a mugger. I’ll update you tomorrow.’

‘Yes, keep me in the loop.’

‘More management speak?’

Hitchens looked up. ‘Sorry?’

‘Nothing, sir.’

Fry made her way to the door, under the impression that her DI had drifted away into some strange seminar-like world of his own, all whiteboards and overhead projectors, with a spicing of motivational role-play.

‘Witnesses,’ said Hitchens suddenly.

‘What?’

‘The sixth lottery ball. Motive, means . . . and witnesses. That’s what you need, some potential witnesses.’

‘I’ve got a whole posse of them,’ said Fry. ‘But without enough bodies available, it’s impossible to question them all. By now, they could have got their stories straight, anyway.’

FRY TURNED THE Peugeot off Castleton Road into Grosvenor Avenue and pulled up at the kerb outside number 12, a once prosperous, detached Victorian villa nestling behind mock porticos. Her flat was on the first floor – a bedroom, sitting room, bathroom with shower cubicle, and a tiny kitchen area. Strangely, the first floor was regarded as the high-status part of the house, poised between the noisier ground-floor flats and the tiny bedsits in the old servants’ quarters on the top floor.

Directly beneath her was a flat full of students. She wasn’t quite sure how many of them shared together – three, perhaps four. The number probably changed from week to week, for all she knew.

When she’d first moved into number 12 Grosvenor Avenue, all the other occupants had been students, most of them studying at High Peak College on the west side of town. But in the past year or two, there had been a gradual population shift, with the students packing their rucksacks and heading for smart new accommodation in the halls of residence that had opened on the college campus. Their replacements seemed to be migrant workers of various nationalities. Many of them were as young as the students, but they were out all day, and often all night, working in hotels and restaurants around Edendale.

Fry took off her jacket and shoes and collapsed on her bed. She must have a shower, or she might never feel human again.

COOPER ARRIVED AT Welbeck Street gasping for a coffee. He felt as though he hadn’t taken a dose of caffeine all day; the briefing before the raid on the cannabis factory seemed so long ago now.