I look again at the computer and the blinking cursor. I am a computer expert and I have written hundreds of programs for mining and predicting data streams, but I can’t use this thing in front of me. I stand.

‘Sorry. I have to go,’ I say to the boy. When he turns his head and his hair flicks in his eyes, I suddenly remember him. Amit. I saw him at the gallery – he gave me oranges, and suddenly I feel a pressing need to remember what happened to them. As I ran from Squire, I left them behind. The thought that they are rotting under mulch makes me unaccountably sad.

‘Have you, erm, tightened the loose screws now?’ he says, pointing at his head and smiling. ‘Remember me?’

‘Of course,’ I say. ‘Thanks for the oranges,’ I add as a convincer, and he smiles again.

I make for the exit. The librarian is there at the desk and opens her mouth to say something but whatever it was, I wave it back into her head. I have to go and get this straightened out in person. There should be police there. The man might be disposing of evidence this second. That could even be where he has gone.

Once off the bus I make quickly for Paddington Green Police Station. I walk in and the smell, a cloying tangle of disinfectant and boiled potatoes meets me.

‘I need to speak to Rachel,’ I say at the desk.

The desk sergeant looks at me. ‘Rachel?’

‘Or her colleague, DI Conway, I need to speak to one of them.’

He looks blankly at me as if I’m speaking in tongues, before languidly tapping on some buttons on a phone.

‘Name?’

‘Shute. Xander Shute.’

‘You want to be careful with a name like that,’ he says, enjoying his own humour. He mumbles into the handset before replacing it. ‘Coming now for you.’

Time drags its heels through the silence and I wait, sinking as I do.

‘Mr Shute?’ I spin around with surprise. I see both detectives.

‘Why haven’t you been?’ I say.

They exchange a look that confuses me.

‘We’ve been trying to get hold of you,’ Blake says.

‘What for?’ I say, following them as they walk to the same room I was interviewed in before.

‘Come, we’ll speak in here,’ Blake says, opening the door for me. The walls, matt black, undulate, making me queasy.

‘The Farm Street crime you reported,’ she says seriously.

I cross my arms and nod. ‘That’s why I’m here,’ I say. ‘Why haven’t you got police there?’

‘You’ve been to the address?’ Conway says, concerned. ‘You shouldn’t be going—’

‘You don’t understand,’ I say. ‘I saw him, the murderer, he’s still there walking around free as a bird. You need to go and arrest him, now.’