Whatever, MacAskill was handsome, with plenty of thick black hair – no grey, no sign of dyeing – and a chiselled face, all angles, the geometry of eyes, nose and chin making it look like he was smiling even when he wasn’t.

‘So,’ the boss said, ‘how does it read to you?’

‘I’m not sure yet. A party gone wrong, a falling out – literally in this case? They hadn’t started on the booze.’

‘Question one in my mind: did they come together? The victim could have come alone, surprised some people doing something they shouldn’t —’

Rebus was shaking his head. ‘Taxi driver confirms dropping off a party of three. Gave descriptions, one of which matches the deceased pretty well. The driver paid him most attention, he was behaving the worst. The other two were quiet, sober even. Physical descriptions aren’t going to get us far. He picked up the fare outside Mal’s Bar. We’ve had a word with the staff. They sold them the carry-out.’

The boss ran a hand down his tie. ‘Do we know anything more about the deceased?’

‘Only that he had Aberdeen connections, maybe worked in the oil business. He didn’t use his Edinburgh flat much, makes me think he used to work heavy shifts, two weeks on, two off. Maybe he didn’t always come home between times. He was earning enough to pay off a mortgage in the Financial District, and there’s a two-week gap between his latest credit-card transactions.’

‘You think he could have been offshore during that time?’

Rebus shrugged. ‘I don’t know if that’s the way it still works, but in the early days I had friends who went to seek their fortune on the rigs. The stints lasted two weeks, seven days a week.’

‘Well, it’s worth following up. We need to check family, too, next of kin. Priority for the paperwork and formal ID. Question one in my mind: motive. Are we sticking with an argument?’

Rebus shook his head. ‘There was too much premeditation, way too much. Did they just happen to find sealing-tape and a polythene bag in that tip? I think they brought them. Do you remember how the Krays got to Jack “the Hat” McVitie? No, you’re too young. They invited him to a party. He’d been paid to do a contract, but bottled it and couldn’t pay them back. It was in a basement, so down he comes crying out for birds and booze. No birds, no booze, just Ronnie grabbing him and Reggie stabbing him to death.’

‘So these two men lured Mitchison to the derelict flat?’

‘Maybe.’

‘To what end?’

‘Well, first thing they did was tie him up and wrap a bag around his head, so they didn’t have any questions to ask. They just wanted him crapping himself and then dead. I’d say it was straight assassination, with a bit of malicious cruelty thrown in.’

‘So was he thrown or did he jump?’

‘Does it matter?’

‘Very much, John.’ MacAskill stood up, leaned against the filing cabinet with his arms folded. ‘If he jumped, that’s tantamount to suicide, even if they had been planning to kill him. With the bag over his head and the way he was trussed up, we’ve got maybe culpable homicide. Their defence would be that they were trying to scare him, he got too scared and did something they hadn’t been expecting – jumped through a window.’