Stuart took a phone from his pocket and flashed up a picture. It was an ID photo of a female police officer, taken from some official personnel file. She was in her early thirties. Good-looking. Her hair was dark, tied back but visibly quite long. ‘Fits your man’s description of the woman at the scene of today’s incident, don’t you think? All in all, clear enough evidence that PC Grace Kirk is mixed up in this somehow.’

Hacker stared at the photo. The scale of the problem was gradually dawning on him. ‘If she’s with the police, then who’s the guy? He can’t be a copper. Coppers don’t blow people away with sawn-offs. Not in this country, anyhow.’

Stuart shook his head, putting the phone away. ‘Whoever he is, he’s just made the mistake of his life, messing with me. Your flight to Italy is now postponed, Hacker. Instead I want you to focus on finding this man before he causes us irreparable damage.’

Hacker asked, ‘What do you suppose they know?’

Stuart replied, ‘They found McGlashan. They’re getting closer. Therefore we have to assume they know everything.’

‘If he’s not a copper, then what’s his motive?’ Hacker said, thinking out loud.

‘He’s obviously after the same thing everyone else is. Money.’

‘Or maybe it’s something else. Maybe he’s a mate of McCulloch’s, come looking for him. An army buddy, perhaps.’

Stuart shook his head. ‘Too big an age gap, surely.’

‘Not if the guy was just starting out on his military career when McCulloch’s was coming to an end. They could still have served together, in the same regiment, at the same time.’ The more Hacker thought about it, the more the pieces of the puzzle seemed to slot together. The likes of Jamie McGlashan couldn’t have got away from him at the loch last night. But an SAS soldier was an entirely different matter. Not to mention the fact that someone of that calibre would be more than a match for a dozen Angus Bairds.

‘That’s all I needed,’ Stuart muttered. ‘What the hell do you propose to do about it, Hacker? Hacker?’

Hacker was momentarily elsewhere, staring into space, his head filled with the image of Kev O’Donnell lying there dead in the snow, covered in blood, ripped apart by a shotgun blast. Then Hacker tried to picture the man who had done this.

You kill one of the brotherhood, you face the penalty.