“So you’re Geraint’s alibi for the time Jasper Chiswell died?”

“I suppose so.”

“And he’s yours.”

“Why would I want Jasper Chiswell dead?” asked Aamir.

“That’s a good question,” said Strike.

“I barely knew the man,” said Aamir.

“Really?”

“Yes, really.”

“So what made him quote Catullus at you, and mention Fate, and intimate in front of a room full of people that he knew things about your private life?”

There was a long pause. Again, Aamir’s eye twitched.

“That didn’t happen,” he said.

“Really? My partner—”

“She’s lying. Chiswell didn’t know anything about my private life. Nothing.”

Strike heard the numb drone of a hoover next door. He had been right. The walls were not thick.

“I’ve seen you once before,” Strike told Mallik, who looked more frightened than ever. “Jimmy Knight’s meeting in East Ham, couple of months ago.”

“I don’t know what you’re talking about,” said Mallik. “You’ve mistaken me for someone else.” Then, unconvincingly, “Who’s Jimmy Knight?”

“OK, Aamir,” said Strike, “if that’s how you want to play it, there’s no point going on. Could I use your bathroom?”

“What?”

“Need a pee. Then I’ll clear out, leave you in peace.”

Mallik clearly wanted to refuse, but seemed unable to find a reason to do so.

“All right,” said Aamir. “But—”

A thought seemed to have occurred to him.

“—wait. I need to move—I was soaking some socks in the sink. Stay here.”

“Right you are,” said Strike.

Aamir left the room. Strike wanted an excuse to poke around upstairs for clues to the entity or activity that might have caused animal noises loud enough to disturb the neighbors, but the sound of Aamir’s footsteps told him that the bathroom lay beyond the kitchen on the ground floor.

A couple of minutes later, Aamir returned.

“It’s through here.”

He led Strike down the hall, through a nondescript, bare kitchen, and pointed him into the bathroom.

Strike entered, closed and locked the door, then placed his hand at the bottom of the sink. It was dry. The walls of the bathroom were pink and matched the pink bathroom suite. Grab rails beside the toilet and a floor-to-ceiling rail at the end of the bath suggested that this had been, some time in the recent past, the home of a frail or disabled person.

What was it that Aamir had wanted to remove or conceal before the detective entered? Strike opened the bathroom cabinet. It contained very little other than a young man’s basic necessities: shaving kit, deodorant and aftershave.

Closing the cabinet, Strike saw his own reflection swing into view and, over his shoulder, the back of the door, where a thick navy toweling robe had been hung up carelessly, suspended from the arm hole rather than the loop designed for that purpose.

Flushing the toilet to maintain the fiction that he was too busy to nose around, Strike approached the dressing gown and felt the empty pockets. As he did so, the precariously placed robe slid off the hook.

Strike took a step backwards, the better to appreciate what had just been revealed. Somebody had gouged a crude, four-legged figure into the bathroom door, splintering the wood and paint. Strike turned on the cold tap, in case Aamir was listening, took a picture of the carving with his mobile, turned off the tap and replaced the toweling robe as he had found it.

Aamir was waiting at the end of the kitchen.

“All right if I take those papers with me?” Strike asked, and without waiting for an answer he returned to the sitting room and picked up the Facebook pages.

“What made you leave the Foreign Office, anyway?” he asked casually.

“I… didn’t enjoy it.”

“How did it come about, you working for the Winns?”

“We’d met,” said Aamir. “Della offered me a job. I took it.”

It happened, very occasionally, that Strike felt scruples about what he was driven to ask during an interview.

“I couldn’t help noticing,” he said, holding up the wad of printed material, “that you seemed to drop out of sight of your family for quite a long time after you left the Foreign Office. No more appearances in group shots, not even on your mother’s seventieth birthday. Your sister stopped mentioning you, for a long time.”

Aamir said nothing.

“It was as if you’d been disowned,” said Strike.

“You can get out, now,” said Aamir, but Strike didn’t move.

“When your sister posted this picture of the pair of you in the pizza place,” Strike continued, unfolding the last sheet again, “the responses were—”

“I want you to leave,” repeated Aamir, more loudly.

“‘What you doing with that scumbag?’ ‘Your dad know you still seeing him?’” Strike read aloud from the messages beneath the picture of Aamir and his sister. “‘If my brother permitted liwat—’”

Aamir charged at him, sending a wild right-handed punch to the side of Strike’s head that the detective parried. But the studious-looking Aamir was full of the kind of blind rage that could make a dangerous opponent of almost any man. Tearing a nearby lamp from its socket he swung it so violently that had Strike not ducked in time, the lamp base could have shattered, not on the wall that half-divided the sitting room, but on his face.

“Enough!” bellowed Strike, as Aamir dropped the remnants of the lamp and came at him again. Strike fended off the windmilling fists, hooked his prosthetic leg around the back of Aamir’s leg, and threw him to the floor. Swearing under his breath, because this action had done his aching stump no good at all, Strike straightened up, panting, and said:

“Any more and I’ll fucking deck you.”

Aamir rolled out of Strike’s reach and got to his feet. His glasses were hanging from one ear. Hands shaking, he took them off and examined the broken hinge. His eyes were suddenly huge.

“Aamir, I’m not interested in your private life,” panted Strike, “I’m interested in who you’re covering up for—”

“Get out,” whispered Aamir.

“—because if the police decide it’s murder, everything you’re trying to hide will come out. Murder inquiries respect no one’s privacy.”

“Get out!”

“All right. Don’t say I didn’t warn you.”

At the front door, Strike turned one last time to face Aamir, who had followed him into the hall, and braced himself as Strike came to a halt.

“Who carved that mark on the inside of your bathroom door, Aamir?”

“Out!”

Strike knew there was no point persisting. As soon as he had crossed the threshold, the front door slammed behind him.

Several houses away, the wincing Strike leaned up against a tree to take the weight off his prosthesis, and texted Robin the picture he had just taken, along with the message:

Remind you of anything?

He lit a cigarette and waited for Robin’s response, glad of an excuse to remain stationary, because quite apart from the pain in his stump, the side of his head was throbbing. In dodging the lamp he had hit it against the wall, and his back was aching because of the effort it had taken to throw the younger man to the floor.