Wardle yawned and stretched.

“I’ve got to get back to the office,” he said. “This could be an all-nighter. We’ve got a load of information coming in now the papers are on to it.”

Strike was extremely hungry now, but the pub was noisy and he felt he would rather eat somewhere he could think. He and Wardle headed up the road together, both lighting fresh cigarettes as they walked.

“The psychologist raised something,” said Wardle as the curtain of darkness unrolled across the sky above them. “If we’re right, and we’re dealing with a serial killer, he’s usually an opportunist. He’s got a bloody good m.o.—he must be a planner to a degree, or he couldn’t have got away with it so often—but there was a change in the pattern with Kelsey. He knew exactly where she was staying. The letters and the fact that he knew there wouldn’t be anyone there: it was totally premeditated.

“Trouble is, we’ve had a bloody good look, but we can’t find any evidence that any of your guys have ever been in proximity with her. We virtually took her laptop apart, and there was nothing there. The only people she ever talked to about her leg were those oddballs Jason and Tempest. She had hardly any friends, and the ones she did have were all girls. There was nothing suspicious on her phone. As far as we know, none of your guys has ever lived or worked in Finchley or Shepherd’s Bush, let alone gone anywhere near her school or college. They’ve got no known connection with any of her associates. How the hell could any of them get close enough to manipulate her without her family noticing?”

“We know she was duplicitous,” said Strike. “Don’t forget the pretend boyfriend who turned out to be pretty real when he picked her up from Café Rouge.”

“Yeah,” sighed Wardle. “We’ve still got no leads on that bloody bike. We’ve put out a description in the press, but nothing.

“How’s your partner?” he added, pausing outside the glass doors of his place of work, but apparently determined to smoke the cigarette down to the last millimeter. “Not too shaken up?”

“She’s fine,” said Strike. “She’s back in Yorkshire for a wedding dress fitting. I made her take the time off: she’s been working through the weekend a lot lately.”

Robin had left without complaint. What was there to stay for, with the press staking out Denmark Street, one lousy paying job and the police now covering Brockbank, Laing and Whittaker more efficiently than the agency ever could?

“Good luck,” said Strike as he and Wardle parted. The policeman raised a hand in acknowledgment and farewell, and disappeared into the large building behind the slowly revolving prism glittering with the words New Scotland Yard.

Strike strolled back towards the Tube, craving a kebab and inwardly deliberating the problem that Wardle had just put to him. How could any of his suspects have got close enough to Kelsey Platt to know her movements or gain her trust?