After Robin had hung up, Strike sat motionless for a while in his dark office. The thought of the semi-digested McDonald’s meal lying inside Rochelle’s bloated corpse had not prevented him consuming two Big Macs, a large box of fries and a McFlurry on the way back from Scotland Yard. Gassy noises from his stomach were now mingling with the muffled thuds of the bass from the 12 Bar Café, which Strike barely noticed these days; the sound might have been his own pulse.

Ciara Porter’s messy, girlish flat, her wide, groaning mouth, the long white legs wrapped tightly around his back, belonged to a life lived long ago. All his thoughts, now, were for squat and graceless Rochelle Onifade. He remembered her talking fast into her phone, not five minutes after she had left him, dressed in exactly the same clothes she had been wearing when they pulled her out of the river.

He was sure he knew what had happened. Rochelle had called the killer to say that she had just lunched with a private detective; a meeting had been arranged over her glittering pink phone; that night, after a meal or a drink, they had sauntered through the dark towards the river. He thought of Hammersmith Bridge, sage green and gold, in the area where she claimed to have a new flat: a famous suicide spot, with its low sides, and the fast-flowing Thames below. She could not swim. Night-time: two lovers play-fighting, a car sweeps by, a scream and a splash. Would anyone have seen?

Not if the killer had iron-clad nerves and a liberal dash of luck; and this was a murderer who had already demonstrated plenty of the former, and an unnerving, reckless reliance on the latter. Defending counsel would undoubtedly argue diminished responsibility, because of the vainglorious overreaching that made Strike’s quarry unique in his experience; and perhaps, he thought, there was some pathology there, some categorisable madness, but he was not much interested in the psychology. Like John Bristow, he wanted justice.

In the darkness of his office, his thoughts veered suddenly and unhelpfully back in time, to the most personal death of all; the one that Lucy assumed, quite wrongly, haunted Strike’s every investigation, coloured every case; the killing that had fractured his and Lucy’s lives into two epochs, so that everything in their memory was cleaved clearly into that which had happened before their mother died, and that which had happened afterwards. Lucy thought he had run away to join the RMP because of Leda’s death; that he had been driven to it by his unsatisfied belief in his stepfather’s guilt; that every corpse he saw in the course of his professional life must recall their mother to his mind; that every killer he met must seem to be an echo of their stepfather; that he was driven to investigate other deaths in an eternal act of personal exculpation.