He and Carmella approached the house, a chunky double-fronted red brick with a wisteria-covered portico over the door, and a neatly landscaped front garden. It was one of those houses that looked too smart to live in, gleaming glossy paintwork on the front door and around the windows, and not a pebble out of place on the gravel driveway. He would put money on them having a weekly organic ‘vegbox’ delivered, and that there’d be skis in the garage and a Polish cleaning girl coming in twice a week.

When Isabel was taken, Patrick had initially been convinced that a ransom demand would imminently follow, but none came. The same with Liam. When a child is taken from a well-off family, the first assumption is that money must be the primary factor. But so far there was no evidence of that, which made these cases not only less fathomable but more frightening. Over the past week, the people in this part of south-west London had become jittery, as though the local branches of Starbucks had been accidentally serving up coffees containing quadruple shots. More than jittery. The people of the borough of Richmond-upon-Thames were terrified.

And the pressure on the police, on MIT9 in particular, was like nothing Patrick had experienced before, even when there’d been a serial rapist-and-murderer slicing lives apart in Sutton, or during the James Lawler case, when a gang of white kids had beaten a black schoolboy to death at 4:30 in the afternoon. With intense media and public interest, this case had immediately been classified as a critical incident, the most high-profile investigation Patrick had been involved in. This was the kind of pressure Bowie and Queen sang about, and the last couple of nights Patrick had gone to bed with that insistent bassline bouncing inside his skull.

He checked his watch. 00:29. As he knocked on the door, his body tapped into its adrenaline reserves. Here we go, he thought. Here comes the rush. He closed his eyes for a second, let it wash over and through him, like a blast of minty air that made his veins tingle and his skin prickle. He cast off his tiredness like a snake sloughing its skin. He was ready now.

Beside him, Carmella yawned.

He shot her a look. ‘Whatever you do, do not yawn in front of this family.’

‘Sorry, sir.’

A uniform opened the door, an expression of mixed recognition and relief passing across her tired features at the sight of Patrick and Carmella.