“I’ve already started doing that,” she said and he heard the latent rebelliousness, the imminent insistence that she wanted to be back on the street.

“And,” said Strike, thinking fast, “I want you to stake out Wollaston Close.”

“Looking for Laing?”

“Exactly. Keep a low profile, don’t stay there after dark and if you see the beanie bloke you get out of there or set off your bloody rape alarm. Preferably both.”

Even Strike’s surliness could not douse Robin’s delight that she was back on board, a fully equal partner in the business.

She could not know that Strike believed and hoped that he was sending her up a dead end. By day and by night he had watched the entrances to the small block of flats, shifting position regularly, using night-vision goggles to scan the balconies and windows. Nothing he had seen indicated that Laing was lurking within: no broad shadow moving behind a curtain, no hint of a low-growing hairline or dark ferret-like eyes, no massive figure swaying along on crutches or (because Strike took nothing for granted when it came to Donald Laing) swaggering along like the ex-boxer he was. Every man who had passed in and out of the building had been scrutinized by Strike for a hint of resemblance to Laing’s JustGiving photograph or to the faceless figure in the beanie hat, and none of them had come close to a match.

“Yeah,” he said, “you get onto Laing and—give me half those Brockbank numbers—we’ll divide them up. I’ll stick with Whittaker. Make sure you check in regularly, OK?”

He heaved himself out of the sofa.

“Of course,” said Robin, elated. “Oh, and—Cormoran—”

He was already on the way to the inner office, but turned.

“—what are these?”

She was holding up the Accutane pills that he had found in Kelsey’s drawer and which he had left in Robin’s in-tray after looking them up online.

“Oh, them,” he said. “They’re nothing.”

Some of her cheeriness seemed to evaporate. A faint guilt stirred. He knew he was being a grumpy bastard. She didn’t deserve it. He tried to pull himself together.

“Acne medication,” he said. “They were Kelsey’s.”

“Of course—you went to the house—you saw her sister! What happened? What did she say?”

Strike did not feel equal to telling her all about Hazel Furley now. The interview felt a long time ago, he was exhausted and still felt unreasonably antagonistic.

“Nothing new,” he said. “Nothing important.”

“So why did you take these pills?”

“I thought they might be birth control… maybe she was up to something her sister didn’t know about.”

“Oh,” said Robin. “So they really are nothing.”

She tossed them into the bin.

Ego made Strike go on: ego, pure and simple. She had found a good lead and he had nothing except a vague idea about the Accutane.

“And I found a ticket,” he said.

“A what?”

“Like a coat check ticket.”

Robin waited expectantly.

“Number eighteen,” said Strike.

Robin waited for a further explanation, but none came. Strike yawned and conceded defeat.