‘Look, if you’re pissed off about the drinking, don’t take him a bottle. You don’t have to be an arse about it.’

I didn’t know whether I was still pissed off about the drinking, or something else. They both drank. Mum and Dad. But the words come loose from nowhere.

‘You didn’t have to put up with him when he was drunk,’ I said.

‘What do you mean?’ he said, looking up at me.

‘You didn’t have him, reeking of—’ and then I stopped, letting the words founder. In the silence that followed, I saw the realisation dawning.

‘What are you saying, Xander?’ he said after a minute.

‘Forget it.’ I headed towards the front door.

‘No, Xander. This is important,’ he said, coming after me. ‘If you’ve got something to say—’

‘See you, Rory. I have to go,’ I said, harassing the locks to work the latch.

He stood, arms folded, behind me. ‘Well? Have you got anything to say?’

‘Mr Shute? Have you got anything to say?’

The screen blinks at me, strobing between the paused frames. I am back in the police station. The video plays on in my head. The number 42B, in brass against the black door. My brain is whirring, making and unmaking connections when they don’t fit. I am familiar with this process. It is, even in the teeth of this madness, comforting having my mind untangling the puzzle.

I know how this resolves itself. Soon, the solution will crystallise and emerge whole. I know my mind will get there: it’s slower than Rory’s, but still good.

I stare at the screen which just looks back. I cast my eyes away and shut them tight.

Untangle it.

The dryness in my throat won’t be swallowed away. I can’t make sense of it. The familiar warmth of resolution doesn’t arrive. My head thuds and the room begins to close in on me.

In every solution, time is a constant. So, what is the answer to this? What can the answer be to this? My heart begins to pick up pace as the realisation descends to its perfect end.

I am finished.

I stare at the screen.

The floor – the Victorian tile – is gone. In its place is smooth, pale grey marble, threaded through with darker veins. The walls are no longer painted cream but one side is entirely mirrored in what looks like a single glazed panel. Reflected against it, the opposite wall is decorated in tiny mosaic tiles. Tiny spots of starlight shine from the ceiling.

My mouth is open but there is nothing to say.