‘I expect you chucked the hoodie and the gloves in a bin and grabbed a taxi, did you? The police never bothered looking for a suited white man who was out and about that night. You went home to your mother’s, you made food for her, you changed the time on her clock and you woke her up. She’s still convinced that the two of you were talking about Charlie – nice touch, John – at the precise moment that Lula plunged to her death.

‘You got away with it, John. You could have afforded to keep paying Rochelle for life. With your luck, Jonah Agyeman might even have died in Afghanistan; you’ve been getting your hopes up every time you’ve seen a picture of a black soldier in the paper, haven’t you? But you didn’t want to trust to luck. You’re a twisted, arrogant fucker, and you thought you could arrange things better.’

There was a long silence.

‘No proof,’ said Bristow, at last. It was so dark in the office now that he was barely more than a silhouette to Strike. ‘No proof at all.’

‘I’m afraid you’re wrong there,’ said Strike. ‘The police should have got a warrant by now.’

‘For what?’ asked Bristow, and he finally felt confident enough to laugh. ‘To search the bins of London for a hoodie that you say was thrown away three months ago?’

‘No, to look in your mother’s safe, of course.’

Strike was wondering whether he could raise the blind quickly enough. He was a long way from a light switch, and the office was very dark, but he did not want to take his eyes off Bristow’s shadowy figure. He was sure that this triple murderer would not have come unprepared.

‘I’ve given them a few combinations to try,’ Strike went on. ‘If they don’t work, I suppose they’ll have to call in an expert to open it. But if I were a betting man, I’d put my money on 030483.’

A rustle, the blur of a pale hand, and Bristow lunged. The knife point grazed Strike’s chest as he slammed Bristow sideways; the lawyer slid off the desk, rolled over and attacked again, and this time Strike fell over backwards in his chair, with Bristow on top of him, trapped between the wall and the desk.

Strike had one of Bristow’s wrists, but he couldn’t see where the knife was: all was darkness, and he threw a punch that hit Bristow hard under the chin, knocking his head back and sending his glasses flying; Strike punched again, and Bristow hit the wall; Strike tried to sit up, with Bristow’s lower body pinning his agonising half-leg to the ground, and the knife struck him hard in the upper arm: he felt it pierce the flesh, and the flow of warm blood, and the white-hot stinging pain.