“I can’t think of any way Darby Sabini could have known what I was doing that evening, unless someone in King’s Cross nick was watching me. And I can’t think why Darby would care, unless someone important had asked him to find out.”

“Find out about DS Fowler’s boy friend,” Joel said hollowly.

“I’m afraid so. I think, if Colthorne suspects he’s got that on me—”

“Oh God. Could he? Is that my fault, my record?”

“Not if he’s talked to Paul,” Aaron said. “As he must have done if he dictated that letter. I, er, had something of an affair at school.”

“Ooh, did you now,” Joel said, a pale shadow of his usual teasing. “Well, shit. So what’s the plan? Darby Sabini puts the frighteners on me, extorts more than I can pay, then lets me know I can get out from under if I grass you up?”

“You spill your guts to Darby, he takes it to Colthorne, Colthorne dismisses me for gross misconduct. I won’t stand a chance,” Aaron said flatly. “I involved you in an ongoing investigation and you’ve got an indecency conviction. I could try to fight it but the insinuations and the press reports would destroy me, even if I was cleared.”

“Yes, but hang on,” Joel said. “How would that make you look like the Sabini nark in King’s Cross?”

“I don’t think that’s his aim any more. I think that was the original plan, but I have since stumbled on something that made it urgent for him to discredit me immediately and comprehensively, even if he has to put himself in debt to Darby Sabini.”

Joel’s eyes were huge. “What thing?”

“You said yourself. The murder he committed. Possibly murders.”

Joel grasped for words for a couple of seconds, then downed the rest of his whisky in an emphatic manner. Aaron shoved the bottle over; Joel shoved it a half-inch back. “If I drink until I feel happy, you’ll be sending me home in a wheelbarrow. Are you sure about this?”

“No,” Aaron said. “I can’t be because it’s all shadows and suspicions. What I know for certain is, in the last couple of weeks my DI—you read his hand too, he’s the obedient bully—has been piling work on me. I’ve been strongly discouraged from pursuing the murder case in which I suspect Colthorne’s involved. You’ve been harassed both by the Sabinis and by my cousin Paul, and Paul is an idiot and a snob. He wouldn’t write a letter at Darby Sabini’s dictation, but he would gladly take help from a gentleman and not question why it was offered. I think Colthorne is the puppet-master behind it all, and I think it’s because he knows or fears I’m on to him.”