Deep in space planets spin and photons speed through nothingness and black holes suck matter into their mysterious cores. And still Katja Vermeer stares at me.

‘I don’t think that’s necessary,’ she finally says. ‘Thank you for your help, though. It’s appreciated.’

She gets up and heads for the door.

‘C’mon. You wouldn’t have this if I hadn’t brought it to you. I can help.’

She stops and stands with her back to me for a few seconds, as if trying to make up her mind. She turns and looks at me.

‘Before I let Jansen contact you I read your file.’

So it’s come to that, has it? People reading my file before dealing with me. And I’m not even sure just how much is in there. Though I’m sure there’s enough.

‘Then you’ll know I’m serious.’

‘I know you’re trouble.’

‘Is it true you made a grown man cry?’

A flicker of a smile. It’s not much but it’s something I can work with.

‘You want me to beg?’ I ask.

There’s that flicker of a smile again. Or maybe it’s an unconscious twitch.

‘No. Wouldn’t make any difference anyway.’

‘Look, if this turns out to be related to the Muller case, then I want to be involved.’

‘I thought you were about to officially leave the police? You’ve cut your deal, you’ll get your early retirement and you can go off and do whatever it is you do. We asked you to go over the file, but that’s it. Leave this to the professionals.’

The door closes behind her and the dog stands watching it in case it opens again, his tail gradually winding down from a full wag to being still. I think of the interviews Hank and I had done with Huisman, the feeling we’d both had that he was the killer, then the alibi which made it impossible, even though it went against our instincts. Something I’ve learnt over the last year is that ignoring your instinct occasionally isn’t going to do you any harm. But ignoring it again and again and again can land you in a very dark place. And right now my instinct is trying to tell me something. I’m just not sure what.

‘C’mon,’ I tell him. ‘We’re not wanted here. Let’s go and see Nellie.’

Nellie de Vries turns her head to look out of the window onto the IJburg, the vast waters separating Amsterdam from Amsterdam-Noord. I follow her gaze. A cargo ship looms on the horizon, dwarfing the ferry that runs between IJplein and Centraal station. Above it all a plane dives fearlessly towards a bank of cloud. I watch as it emerges unscathed on the other side.

At my feet the dog stirs as if he’s just felt a disturbance in the Force.