Bain lifted another sheet, waved it, smiling. Rebus had to get up again, go fetch it.

T-Bird Oil got its name from Thom Bird, who had been co-founder with ‘Major’ Randall Weir.

‘Major?’

Bain shrugged. ‘That’s what they call him: Major Weir.’

Weir and Bird were both Americans, but with strong Scottish roots. Bird had died in 1986, leaving Weir in charge. It was one of the smaller companies hoovering up oil and gas from below the sea bed …

Rebus realised that he knew almost nothing about the oil industry. He had some pictures in his head, mostly disasters – Piper Alpha, the Braer.

T-Bird had its UK base in Aberdeen, near Dyce Airport, but the global HQ was in the US, and the company held other oil and gas interests in Alaska, Africa, and the Gulf of Mexico.

‘Boring, eh?’ Maclay offered.

‘Is that meant to be a joke?’

‘Just making conversation.’

Rebus got to his feet, put his jacket on. ‘Well, much as I could listen to your dulcet tones all day …’

‘Where are you going?’

‘Station to station.’

No one seemed very interested in his return to St Leonard’s; a couple of woolly suits stopped to say hello – it turned out they didn’t even know he’d been transferred.

‘I don’t know who that says more about – me or you.’

In the CID offices he saw Siobhan Clarke at her desk. She was on the phone, and waved her pen at him as he passed. She wore a white short-sleeved blouse, and her bare arms were deeply tanned, as were her neck and face.

Rebus kept looking, and acknowledged a few lukewarm greetings. Jings, but it was rare to be ‘home’. He thought of Allan Mitchison and his empty flat: he’d come back to Edinburgh because it was as close to a home as he had.

Eventually he spotted Brian Holmes, chatting up a WPC, giving it plenty.

‘Hello, Brian, how’s the wife?’

The WPC turned red, mumbled some excuse and left.

‘Ha fucking ha,’ Holmes said. Now that the WPC had gone, he looked dead done in, shoulders slumped, skin grey, specks of stubble left behind by a too-casual razor.

‘That favour …’ Rebus prompted.

‘I’m on it.’

‘And?’

‘I’m on it!’

‘Go easy, son, we’re all friends here.’

Holmes seemed to deflate. He rubbed his eyes, clawed fingers through his hair.

‘Sorry,’ he said. ‘I’m beat, that’s all it is.’

‘Would coffee help?’

‘Only if you can buy it by the vat.’

The canteen could stretch to an ‘Extra Large’. They sat down, Holmes tearing open sachets of sugar and pouring them in.

‘Look,’ he said, ‘about the other night, Mental Minto …’

‘We don’t talk about that,’ Rebus said firmly. ‘It’s history.’

‘Too much history around here.’

‘What else have the Scots got?’

‘You two look about as happy as nuns on a Club 18–30.’ Siobhan Clarke pulled out a chair and sat down.

‘Nice holiday?’ Rebus asked.

‘Relaxing.’

‘I see the weather was lousy.’