‘Forensics subsequently found McDiarmid’s blood in one of Frankie Callahan’s dark blue catering supply vans,’ said Abercorn. ‘It was parked outside the depot where Callahan, Fleeting and Miller were found dead.’

‘And prior to that,’ Fallan said, ‘did you have any other corroboration of that information?’

‘No,’ Catherine realised. ‘Now I come to think of it, Cairns was the only source of that information. Though if it was a fit-up, how would they get McDiarmid’s blood inside one of Callahan’s vans?’

‘Easy,’ said Fallan. ‘If they’re the ones who killed McDiarmid.’

‘But why would they …’ she began to ask, before she saw precisely why. ‘A phoney tit-for-tat. They murder McDiarmid, knowing Fleeting will be in the frame because McDiarmid was sleeping with Fleeting’s girlfriend. Then there’s a motive for Paddy Steel to have killed Fleeting and Callahan.’

‘And the reason they need them dead is so they’re not around to ask what happened to all their heroin,’ suggested Abercorn. ‘That question was supposed to be covered – or at least shrouded in mystery – by the discovery of the decoy suitcase. Which was why Miller had to die too: he knew there was a real shipment coming into the station that day. And why Cairns went overboard on the search for Whitaker: he wasn’t supposed to be there.’

‘The big question is who else was there,’ Catherine told Fallan. ‘Who were these other cops? We came to you because we know Cairns worked with your father. We want to know who might be in on this, and how far up it might go. Cairns’ mate from the Drug Squad, Fletcher, is top of our list, as they’ve worked together off and on for as long as anybody can remember, although not back in Gallowhaugh. We know your dad also worked with Bill Raeside and Graeme Sunderland. Those names ring any bells?’

Fallan nodded solemnly, sitting back in his chair. There was a lot going on behind his eyes, only a fraction of which she expected him to share.

‘Bill Raeside – or Wullie, as he was in those days – was the shitebag’s shitebag. Born to do as he’s told. Never a trigger man, but he’d be happy to reap the benefits and provide logistical support.’

‘Raeside was the first officer on the scene when McDiarmid’s body was discovered,’ Laura recalled.

‘More than that,’ Catherine admitted. ‘He made sure Locust weren’t informed, and specifically suggested to Sunderland that I be given the case.’

‘What’s Locust?’ asked Jasmine.

‘My department,’ explained Abercorn. ‘Organised Crime Special Task Force. Why would he specifically suggest you take the case?’

Catherine fumed as she admitted that once again she had been played.

‘They must have guessed that an apparent motive concerning petty gangland feuding would suit my sensibilities.’

She felt Fallan’s gaze.

‘They thought you wouldn’t look a gift horse in the mouth,’ he said, and clearly understood why.