Outside, Jack made for the car, but Rebus had other plans. He went into a shop and came out with six cans of Irn-Bru, not diet, then marched back into the station. The desk sergeant was sweating. Rebus handed him the carrier bag.

‘You shouldn’t have,’ the sergeant said.

‘They’re for Jim MacAskill,’ Rebus said. ‘I want at least five to reach him.’

Now he was ready to go.

The Commonwealth Pool, which had been built for the Commonwealth Games in 1970, was sited at the top of Dalkeith Road, at the foot of Arthur’s Seat, and just over quarter of a mile from St Leonard’s police station. In the days when he swam, Rebus used the Commie Pool at lunchtimes. You found yourself a lane – never an empty lane, it was like easing out of a slip-road on to a motorway – and you swam, pacing yourself so you didn’t catch up with the person in front, or let the person behind gain on you. It was OK, but a bit too regimented. The other option was to swim breadths in the open pool, but then you were in with the kids and their parents. There was a separate pool for infants, plus three flumes Rebus had never been down, and elsewhere in the building were saunas, gym, and a café.

They found a space in the overflow car park and went in by the main entrance. Rebus showed ID at the kiosk and gave a description of Shankley.

‘He’s a regular,’ the woman told him.

‘Is he here just now?’

‘I don’t know. I’ve only just come on.’ She turned to ask the other woman in the booth, who was counting coins into polythene bank-bags. Jack Morton tapped Rebus’s arm and nodded.

Beyond the kiosk there was a wide open space, with windows looking down on to the main pool. And standing there, glugging Coke from the can, stood a very tall, very thin man with damp, bleached hair. He had a rolled-up towel under one arm. When he turned, Rebus saw that his eyebrows and lashes were fair. Shankley saw two men examining him, placed them immediately. When Rebus and Morton started towards him, he ran.

He turned a corner into the open-plan café, but couldn’t see an exit from there, so kept running, ended up beside the children’s play area. This was a large netted enclosure totalling three storeys, with slides and walkways and other challenges – a toddler assault course. Rebus liked sometimes to sit with a post-swim coffee watching the kids playing, wondering which would make the best soldier.

Shankley was cornered and knew it. He turned to face them: Rebus and Jack were smiling. The impulse to flee was still too strong: Shankley pushed past the attendant, opened the door to the play area, ducked and went in. Two huge padded rollers stood directly in front of him, like a giant mangle. He was thin enough to squeeze between them.

Jack Morton laughed. ‘Where’s he going to go from there?’