He’s wittering on about not being back late when Luke says, ‘I’ve met someone, but it’s new and it’s tricky, and I’m not sure what’s going to happen. She’s a parent at the school.’

The old Dan would have raised an eyebrow at the parent thing, but he’s sleeping with a former client, so he says nothing, and Luke carries on: ‘She’s … It’s … I don’t know. She’s something.’

‘You always say that,’ Dan says, with affection, and cuffs Luke on the shoulder.

‘No, man, I mean it. This one is different. She’s special.’

‘That’s exactly what you said about the tiny girl with the blue hair who worked at the library. You said, and I quote, “She’s so perfect. You know how long I’ve been looking for my Smurfette.” Remember?’

‘Yes, but I didn’t mean it then,’ Luke says, sounding sulky.

‘And you said the same thing about your teaching assistant with the long hair. You said she was the perfect Princess Leia and smelt of pick ’n’ mix.’

Luke grins at that. ‘Ah, sweet Lydia and her long Leia hair.’ He shakes his head. ‘But seriously, dude, Lizzie is not like them. She’s super-clever – she knows the most random stuff. She’s grown-up. She’s hot.’

Dan smiles indulgently and pats his cousin’s arm. ‘Okay, buddy. Enjoy your serial killer. I’ll give it a week.’

‘I’m being serious, Dan. She’s different. She’s not trying to be anybody else, you know? She doesn’t care about impressing people, even though she’s a crazy genius. She’s not … performing for anyone. She makes me think I don’t need to perform either.’

Luke is hurt and immediately Dan feels contrite. ‘Sorry,’ he says, while the cogs inside whirl. Luke is a natural performer: he seems to love being centre stage, on display. Has that all been an act? Has Luke been hiding in plain sight?

‘We haven’t even slept together yet. I want it to mean something when we do. If she even wants to … She’s got scars, from her ex-husband, on her arms. She ran away from him. I don’t know much and I don’t want to push her, you know?’

‘Wow.’ Dan’s face creases with concern. He hadn’t expected that. ‘That’s a lot to deal with, Luke. Are you sure you know what you’re taking on?’ It’s the wrong thing to say: Dan realizes this as soon as the words have left his mouth. ‘I didn’t mean it the way it sounded.’

‘Patronizing much? I think you did,’ Luke says coldly, turning to walk away.

‘Wait, Luke, please, let’s talk this through.’

‘I’m not one of your clients.’

‘I know. I’m sorry. Truly. I just don’t want you to get hurt or caught up in something that seems … complicated.’