‘Moving on. Item of evidence two is a video clip. Showing the moment that five members of the Castagna gang were killed. We obtained this from Joe Castagna’s laptop after his spectacularly violent demise in what appears to have been a gang turf war that went nuclear on him. It was confiscated as part of a wide-ranging investigation into his death. Mr Castagna seems to have had sources inside the Met.’

Irving picked up a remote control. Pressed the play button. And there he was, climbing out of the Astra all those weeks before. Rendered anonymous by the balaclava. Going into action without any hesitation. Putting down the four gang members inside a ten-count. Irving paused the video.

‘The killer looks about the same height and build as you, Sergeant. Excellent marksmanship too, well up to your proven abilities. No spray and pray, which is what you’d expect from a gang banger. Four precisely placed three-round bursts, which killed four men. Two immediately, one soon after the police arrived, and one before he reached hospital. And then…’

He pressed play again. And all present watched Mickey make the fifth kill. The reluctance with which he waited until he had no other choice.

‘And that’s not in keeping with a gang hit either. Is it?’

Mickey looked across the table. Raising his hands in bafflement. ‘I wouldn’t know, not having ever seen a gang killing. Or had any professional exposure to contract killing, which is what that looked like.’

‘You can take it from me, Sergeant, that—’

‘I’m happy to be told what you think it looks like, Chief Inspector.’

Mickey sat back, resisting the urge to smirk at Jasmine. Or even look at her. Irving looked at him, blank-faced, for a moment. Then resumed his line of attack.

‘That last kill was reluctant. It would be easier to shoot the sort of thugs Joe Castagna employed than putting three rounds into a child, I suppose.’

‘A child? He had a beard.’

‘He was seventeen. Which would have been obvious enough, if you were looking at him over the barrel of a machine pistol from six feet away. And then, of course, we have the younger brother.’

Irving was watching him intently. As was Haskins. Mickey’s instincts told him there was a twist coming. The DAC took up the running.

‘We’ve met the child. We requested permission to speak to him, once the dust had settled on Joe Castagna’s somewhat spectacular murder.’ Here it came. Professional Standards’ ace-in-the-hole evidence Mickey had been waiting for. ‘Samuel claimed that the Car Park Killer spoke to him. Which is corroborated by this video footage. It seems Castagna put him on a retainer. Which his mother discovered when he came home in box-fresh Nikes. She reported it to us; we interviewed him again. It seems that Castagna planned to use him to identify the Car Park Killer, if he came up with a suspect.’