“Are you ignoring me on purpose?”

“What?”

It was just plausible that he had not heard her, so noisy was the old Land Rover’s engine.

“I said, how are things with Elin?”

She had never asked him outright about a relationship before. Strike supposed the confidences of two nights ago had moved them onto a different level of intimacy. He would have avoided this, if he could.

“All right,” he said repressively, throwing away his cigarette butt and pulling up the window, which marginally reduced the noise.

“She forgave you, then?”

“What for?”

“For completely forgetting that you had a date!” said Robin.

“Oh, that. Yeah. Well, no—then, yeah.”

As she turned onto the A40, Strike’s ambiguous utterance brought to Robin a sudden, vivid mental image: of Strike, with his hairy bulk and his one and a half legs, entangled with Elin, blonde and alabaster against pure white sheets… she was sure that Elin’s sheets would be white and Nordic and clean. She probably had somebody to do her laundry. Elin was too upper middle class, too wealthy, to iron her own duvet covers in front of the TV in a cramped sitting room in Ealing.

“How about Matthew?” Strike asked her as they moved out onto the motorway. “How’d that go?”

“Fine,” said Robin.

“Bollocks,” said Strike.

Though another laugh escaped her, Robin was half inclined to resent his demand for more information when she was given so little about Elin.

“Well, he wants to get back together.”

“Course he does,” said Strike.

“Why ‘of course’?”

“If I’m not allowed to fish, you aren’t.”

Robin was not sure what to say to that, though it gave her a small glow of pleasure. She thought it might be the very first time that Strike had ever given any indication that he saw her as a woman, and she silently filed away the exchange to pore over later, in solitude.

“He apologized and kept asking me to put my ring back on,” Robin said. Residual loyalty to Matthew prevented her mentioning the crying, the begging. “But I…”

Her voice trailed away, and although Strike wanted to hear more, he asked no further questions, but pulled down the window and smoked another cigarette.

They stopped for a coffee at Hilton Park Services. Robin went to the bathroom while Strike queued for coffees in Burger King. In front of the mirror she checked her mobile. As she had expected, a message from Matthew was waiting, but the tone was no longer pleading and conciliatory.

If you sleep with him, we’re over for good. You might think it’ll make things even but it’s not like for like. Sarah was a long time ago, we were kids and I didn’t do it to hurt you. Think about what you’re throwing away, Robin. I love you.

“Sorry,” Robin muttered, moving aside to allow an impatient girl access to the hand-dryer.

She read Matthew’s text again. A satisfying gush of anger obliterated the mingled pity and pain engendered by that morning’s pursuit. Here, she thought, was the authentic Matthew: if you sleep with him, we’re over for good. So he did not really believe that she had meant it when she took off her ring and told him she no longer wished to marry him? It would be over “for good” only when he, Matthew, said so? It’s not like for like. Her infidelity would be worse than his by definition. To him, her journey north was simply an exercise in retaliation: a dead woman and a killer loose mere pretext for feminine spite.