Back on Charing Cross Road, limping on to the office through the temporary shadow of the pedestrian tunnel, he remembered the way that Robin had woken him up that morning: the tactful knock, the cup of tea, the studied avoidance of the subject of the camp bed. He ought not to have let it happen. There were other routes to intimacy than admiring a woman’s figure in a tight dress. He did not want to explain why he was sleeping at work; he dreaded personal questions. And he had let a situation arise in which she had called him Cormoran and told him to do up his buttons. He ought never to have overslept.

As he climbed the metal stairs, past the closed door of Crowdy Graphics, Strike resolved to treat Robin with a slightly cooler edge of authority for the rest of the day, to counterbalance that glimpse of hairy belly.

The decision was no sooner made than he heard high-pitched laughter, and two female voices talking at the same time, issuing from his own office.

Strike froze, listening, panicking. He had not returned Charlotte’s call. He tried to make out her tone and inflection; it would be like her to come in person and overwhelm his temp with charm, to make of his ally a friend, to saturate his own staff with Charlotte’s version of the truth. The two voices melded in laughter again, and he could not tell whose they were.

‘Hi, Stick,’ said a cheery voice as he pushed open the glass door.

His sister, Lucy, was sitting on the sagging sofa, with her hands around a mug of coffee, bags from Marks and Spencer and John Lewis heaped all around her.

Strike’s first surge of relief that she was not Charlotte was nevertheless tainted with a lesser dread of what she and Robin had been talking about, and how much each of them now knew about his private life. As he returned Lucy’s hug, he noticed that Robin had, again, closed the inner door on the camp bed and kitbag.

‘Robin says you’ve been out detecting.’ Lucy seemed in high spirits, as she so often was when she was out alone, unencumbered by Greg and the boys.

‘Yeah, we do that sometimes, detectives,’ said Strike. ‘Been shopping?’

‘Yes, Sherlock, I have.’

‘D’you want to go out for a coffee?’

‘I’ve already got one, Stick,’ she said, holding up the mug. ‘You’re not very sharp today. Are you limping a bit?’

‘Not that I’ve noticed.’

‘Have you seen Mr Chakrabati recently?’

‘Fairly recently,’ lied Strike.

‘If it’s all right,’ said Robin, who was putting on her trench coat, ‘I’ll take lunch, Mr Strike. I haven’t had any yet.’

The resolution of moments ago, to treat her with professional froideur, now seemed not only unnecessary but unkind. She had more tact than any woman he had ever met.