‘Seriously, have a great time. Let your hair down. And I’m putting that name in the envelope now.’

‘Waste of a good envelope,’ says Naylor.

The bar at Alfonso’s is packed with people Naylor barely recognises as those she shares an office with day-to-day. She’s glad she kept the red dress; she feels good in it, and it’s pulling one or two glances as she makes her way to where Rose is talking to Hagen and a crowd of others from the department. All of them look smart, relaxed, normal, just punters on a night out, a regular office party. Hagen puts a glass of wine in her hand, and as she takes the first sip, she hears a blast of laughter from a group near the door. Dallabrida’s first joke of the night.

Dinner, as it turns out, isn’t bad – essentially beef in red wine but with Italianate touches, breadsticks and pasta, curly endive in the salad and tiramisu at the end. By the time coffee’s served, Naylor’s enjoying herself, and in a moment of lucidity, she realises why. Last year, she’d spent half the evening in the toilets, obsessively checking her phone for a message from him. This year, she’s free of that compulsion. Anyone she might be interested in is in this room.

People begin to drift back to the bar, and the DJ fires up. The music’s loud and upbeat, and with the laughter and the alcohol they’ve already drunk, she and Rose are thinking they might order more prosecco. Naylor bends down to find her bag and hunt for cash. When she resurfaces, someone’s standing by her chair.

‘Looking good, Miss Rachel,’ says Dallabrida. ‘Red is most definitely your colour.’

Naylor finds herself smiling. Dallabrida’s looking pretty good himself, decked out as he promised in a tuxedo with all the works.

‘Nice threads,’ she says, pointing to his jacket.

‘I’ve got me dancin’ shoes on an’ all,’ he says. ‘You fancy comin’ with me for a test drive?’

As Naylor steps with Dallabrida on to the dance floor, Ron Perdue carries a large glass of Merlot into his study, sits down at his laptop and opens up the file of notes he made on the Ferrers enquiry.

It’s all in here, everything on the red Ford Focus and the places he visited.

Where did he go first? Sevenoaks, on the trail of Jennifer Lambert, to those grubby flats with the addict on the ground floor.

He reads through the notes he made. There isn’t much, just a mention of a South African doctor and Ms Lambert’s probable emigration, and his observation that he thought she was unconnected to the enquiry, a turned-over stone with nothing underneath.