Right now I was way out of my comfort zone. A renegade copper. A law breaker. But I didn’t feel uncomfortable. And I didn’t feel any guilt or shame. It might have been different if I’d been willing to accept the possibility that Slack had been telling the truth all along and he didn’t know anything. But I wasn’t because I’d convinced myself that it couldn’t be anyone but him. And nothing I’d seen or heard had caused me to change my mind.

‘It’s just come to me,’ Carver said. ‘You’re the bird who turned up at the office. Jefferson. It was your bloke who was shot in Balham. The teacher.’

He made it sound like it was no big deal. And that made the anger tremble inside me. So I kicked him again. In the stomach. And as he writhed on the floor, I said, ‘Tell me what you know, Carver. Or so help me I will …’

He screwed his face into a snarl. ‘You’ll what, copper? Kill me? I don’t fucking think so. You ain’t got the bottle.’

I pulled back my coat hood and ripped off my scarf. I’d hoped that I’d be able to do this without revealing my identity, but now I didn’t care if he saw my face. In fact I suddenly wanted him to.

‘You have no idea what I’m capable of,’ I roared at him. ‘Your boss tried to have me murdered. He got someone to assassinate the Commissioner and kill one of my colleagues. So do you really think I’d balk at putting you six feet under? Especially since nobody knows I’m here and every cop in this city would give me an alibi if I needed one.’

His jaw tightened as he continued to stare at me without blinking. He was sizing me up, trying to work out if I was angry enough and reckless enough to take this much further.

I held his steely gaze, determined not to show any weakness or hesitation. I wanted him to know that I wasn’t about to lose my nerve. That I’d been pushed beyond reason and didn’t care about the consequences of my actions.

‘You won’t get me to admit to anything,’ he said after a few seconds. ‘And this psycho act is wasted on me. I can see you have a temper like most bitches. But you don’t have the stomach to see this through. It takes a certain kind of person to torture a confession out of someone. You have to be like me, and you’re not.’

‘This false bravado won’t wash,’ I said. ‘We both know that when the pain gets bad enough you’ll open up. And I’m more than prepared to inflict it even though I don’t regard myself as a complete psychopath.’