Four days later, at lunchtime, Strike was to be found leaning up against a counter in a tiny takeaway pizza restaurant, which was most conveniently situated for watching a house directly across the street. One of a pair of brown brick semi-detached houses, the name “Ivy Cottages” was engraved in stone over the twin doors, which seemed to Strike more fitting for humbler dwellings than these houses, which had graceful arched windows and corniced keystones.

Chewing on a slice of pizza, Strike felt his phone vibrate in his pocket. He checked to see who was calling before answering, because he had already had one fraught conversation with Lorelei today. Seeing that it was Robin, he answered.

“I’m in,” said Robin. She sounded excited. “Just had my interview. The owner’s dreadful, I’m not surprised nobody wants to work for her. It’s a zero-hours contract. Basically, she wants a couple of people to fill in whenever she fancies not working.”

“Flick still there?”

“Yes, she was manning the counter while I was talking to the shop owner. The woman wants to give me a trial tomorrow.”

“You weren’t followed?”

“No, I think that journalist has given up. He wasn’t here yesterday either. Mind you, he probably wouldn’t have recognized me even if he’d seen me. You should see my hair.”

“Why, what have you done with it?”

“Chalk.”

“What?”

“Hair chalk,” said Robin. “Temporary color. It’s black and blue. And I’m wearing a lot of eye makeup and some temporary tattoos.”

“Send us a selfie, I could do with some light relief.”

“Make your own. What’s going on your end?”

“Bugger all. Mallik came out of Della’s house with her this morning—”

“God, are they living together?”

“No idea. They went out somewhere in a taxi with the guide dog. They came back an hour ago and I’m waiting to see what happens next. One interesting thing, though: I’ve seen Mallik before. Recognized him the moment I saw him this morning.”

“Really?”

“Yeah, he was at Jimmy’s CORE meeting. The one I went to, to try and find Billy.”

“How weird… D’you think he was acting as a go-between for Geraint?”

“Maybe,” said Strike, “but I can’t see why the phone wouldn’t have done if they wanted to keep in touch. You know, there’s something funny about Mallik generally.”

“He’s all right,” said Robin quickly. “He didn’t like me, but that was because he was suspicious. That just means he’s sharper than most of the rest of them.”

“You don’t fancy him as a killer?”

“Is this because of what Kinvara said?”

“‘My husband provoked somebody, somebody I warned him he shouldn’t upset,’” Strike quoted.

“And why should anyone be particularly worried about upsetting Aamir? Because he’s brown? I felt sorry for him, actually, having to work with—”

“Hang on,” said Strike, letting his last piece of pizza fall back onto the plate.

The front door of Della’s house had opened again.

“We’re off,” said Strike, as Mallik came out of the house alone, closed the door behind him, walked briskly down the garden path, and set off down the road. Strike headed out of the pizzeria in pursuit.

“Got a spring in his step now. He looks happy to be away from her…”

“How’s your leg?”

“It’s been worse. Hang on, he’s turning left… Robin, I’m going to go, need to speed up a bit.”

“Good luck.”

“Cheers.”

Strike crossed Southwark Park Road as quickly as his leg permitted, then turned into Alma Grove, a long residential street with plane trees planted at regular intervals, and Victorian terraced houses on both sides. To Strike’s surprise, Mallik stopped at a house on the right, with a turquoise door, and let himself inside. The distance between his place of residence and that of the Winns’ was five minutes’ walk at most.

The houses in Alma Grove were narrow and Strike could well imagine loud noises traveling easily through the walls. Giving Mallik what he judged to be sufficient time to remove his jacket and shoes, Strike approached the turquoise door and knocked.

After a few seconds’ wait, Aamir opened up. His expression changed from pleasant inquiry to shock. Aamir evidently knew exactly who Strike was.

“Aamir Mallik?”

The younger man did not speak at first, but stood frozen with one hand on the door, the other on the hall wall, looking at Strike with dark eyes shrunken by the thickness of the lenses in his glasses.

“What do you want?”

“A chat,” said Strike.

“Why? What for?”

“Jasper Chiswell’s family have hired me. They aren’t sure he committed suicide.”

Appearing temporarily paralyzed, Aamir neither moved nor spoke. Finally, he stood back from the door.

“All right, come in.”

In Aamir’s position, Strike too would have wanted to know what the detective knew or suspected, rather than wondering through fretful nights why he had called. Strike entered and wiped his feet on the doormat.

The house was larger inside than it had appeared outside. Aamir led Strike through a door on the left into a sitting room. The décor was, very obviously, the taste of a person far older than Aamir. A thick, patterned carpet of swirling pinks and greens, a number of chintz-covered chairs, a wooden coffee table with a lace cloth laid over it and an ornamental edged mirror over the mantelpiece all spoke of geriatric occupants, while an ugly electric heater had been installed in the wrought iron fireplace. Shelves were bare, surfaces denuded of ornaments or other objects. A Stieg Larsson paperback lay on the arm of a chair.

Aamir turned to face Strike, hands in the pockets of his jeans.

“You’re Cormoran Strike,” he said.

“That’s right.”

“It was your partner who was pretending to be Venetia, at the Commons.”

“Right again.”

“What d’you want?” Aamir asked, for the second time.

“To ask you a few questions.”

“About what?”

“OK if I sit down?” asked Strike, doing so without waiting for permission. He noticed Aamir’s eyes drop to his leg, and stretched out the prosthesis ostentatiously, so that a glint of the metal ankle could be seen above his sock. To a man so considerate of Della’s disability, this might be sufficient reason not to ask Strike to get up again. “As I said, the family doesn’t think Jasper Chiswell killed himself.”

“You think I had something to do with his death?” asked Aamir, trying for incredulity and succeeding only in sounding scared.

“No,” said Strike, “but if you want to blurt out a confession, feel free. It’ll save me a lot of work.”

Aamir didn’t smile.

“The only thing I know about you, Aamir,” said Strike, “is that you were helping Geraint Winn blackmail Chiswell.”

“I wasn’t,” said Aamir at once.

It was the automatic, ill-considered denial of a panicked man.

“You weren’t trying to get hold of incriminating photographs to use against him?”

“I don’t know what you’re talking about.”

“The press are trying to break your bosses’ super-injunction. Once the blackmail’s out in the public domain, your part in it won’t remain hidden for long. You and your friend Christopher—”

“He’s not my friend!”

Aamir’s vehemence interested Strike.

“D’you own this house, Aamir?”

“What?”

“Just seems a big place for a twenty-four-year-old on what can’t be a big salary—”

“It’s none of your business who owns this—”

“I don’t care, personally,” said Strike, leaning forwards, “but the papers will. You’ll look beholden to the owners if you aren’t paying a fair rent. It could seem like you owed them something, like you’re in their pocket. The tax office will also consider it a benefit in kind if it’s owned by your employers, which could cause problems for both—”

“How did you know where to find me?” Aamir demanded.

“Well, it wasn’t easy,” Strike admitted. “You don’t have much of an online life, do you? But in the end,” he said, reaching for a sheaf of folded paper in the inside pocket of his jacket, and unfolding them, “I found your sister’s Facebook page. That is your sister, right?”

He laid the piece of paper, on which he had printed the Facebook post, on the coffee table. A plumply pretty woman in a hijab beamed up out of the poor reproduction of her photograph, surrounded by four young children. Taking Aamir’s silence for assent, Strike said:

“I went back through a few years’ worth of posts. That’s you,” he said, laying a second printed page on top of the first. A younger Aamir stood smiling in academic robes, flanked by his parents. “You took a first in politics and economics at LSE. Very impressive…

“And you got onto a graduate training program at the Foreign Office,” Strike continued, placing a third sheet down on top of the first two. This showed an official, posed photograph of a small group of smartly dressed young men and women, all black or from other ethnic minorities, standing around a balding, florid-faced man. “There you are,” said Strike, “with senior civil servant Sir Christopher Barrowclough-Burns, who at that time was running a diversity recruitment drive.”

Aamir’s eye twitched.

“And here you are again,” said Strike, laying down the last of his four printed Facebook pages, “just a month ago, with your sister in that pizza place right opposite Della’s house. Once I identified where it was and realized how close it was to the Winns’ place, I thought it might be worth coming to Bermondsey to see whether I could spot you in the vicinity.”

Aamir stared down at the picture of himself and his sister. She had taken the selfie. Southwark Park Road was clearly visible behind them, through the window.

“Where were you at 6 a.m. on the thirteenth of July?” Strike asked Aamir.

“Here.”

“Could anyone corroborate that?”

“Yes. Geraint Winn.”

“Had he stayed the night?”

Aamir advanced a few steps, fists raised. It could not have been plainer that he had never boxed, but nevertheless, Strike tensed. Aamir looked close to breaking point.

“All I’m saying,” said Strike, holding up his hands pacifically, “is that 6 a.m. is an odd time for Geraint Winn to be at your house.”

Aamir slowly lowered his fists, then, as though he did not know what else to do with himself, he backed away to sit down on the edge of the seat of the nearest armchair.

“Geraint came round to tell me Della had had a fall.”

“Couldn’t he have phoned?”

“I suppose so, but he didn’t,” said Aamir. “He wanted me to help him persuade Della to go to casualty. She’d slipped down the last few stairs and her wrist was swelling up. I went round there—they only live round the corner—but I couldn’t persuade her. She’s stubborn. Anyway, it turned out to be only a sprain, not a break. She was fine.”

“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:

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.

Strike glanced back at the turquoise door. If he was honest, something else was hurting: his conscience. He had entered Mallik’s house with the intention of shocking or intimidating him into the truth about his relationship with Chiswell and the Winns. While a private detective could not afford the doctor’s dictum “first, do no harm,” Strike generally attempted to extract truth without causing unnecessary damage to the host. Reading out the comments at the bottom of that Facebook post had been a low blow. Brilliant, unhappy, undoubtedly tied to the Winns by something other than choice, Aamir Mallik’s eruption into violence had been the reaction of a desperate man. Strike didn’t need to consult the papers in his pocket to recall the picture of Mallik standing proudly in the Foreign Office, about to embark on a stellar career with his first-class degree with his mentor, Sir Christopher Barrowclough-Burns, by his side.

His mobile rang.

“Where on earth did you find that carving?” said Robin.

“The back of Aamir’s bathroom door, hidden under a dressing gown.”

“You’re joking.”

“No. What does it look like to you?”

“The white horse on the hill over Woolstone,” said Robin.

“Well, that’s a relief,” said Strike, elbowing himself off the supporting tree and limping off along the street again. “I was worried I’d started hallucinating the bloody things.”