‘Try them all. I will too.’ I was still on my knees, at the wrong attitude to exert much force, but pressing and pushing I tried to shift the wooden floor. Or the trap cover, as I had to assume. I felt it move slightly. ‘Try that again!’ I yelled down to Spoder.

The screen at the front of the cabinet started to close. It had real pressure behind it, the hydraulics irresistible. I scrambled backwards urgently, dreading what would happen if I too was caught in the mechanism. The screen closed.

I searched for the key, suddenly panicking that I might have dropped it irretrievably inside the cabinet. Then thankfully I found it, re-opened the screen.

Spoder’s head was surprisingly now visible in the main part of the cabinet. It was all I could see of him. The rest of him was below ground level.

‘Please help me out of here, sir!’

He managed to disentangle one of his arms and pushed it up. After a painful struggle he brought up the second one. In the confined space as I leaned into the cabinet it was almost impossible to get a lifting grip on him, but I pulled as I could while Spoder struggled below. He was much heavier than I had imagined, and his constant bellowing of frightened orders at me, and struggling with his elbows and arms, multiplied the problem of trying to hold and lift him.

Finally it was done somehow, and Spoder and I pushed back and away from the cabinet and sprawled together on the hard carpeted floor. One of his bare legs ended up beside me. I saw a smear of something old, brown and powdery, on his skin. When he saw me looking he sat up and brushed it away with a hand. He stood up, favouring his left leg. He rubbed his right ankle.

‘So that’s where they found Willer’s body?’ I said. Behind us the cabinet front screen was closing.

The screams from the Scrambler next door had ceased, but the music was still playing at maximum volume. After a few more seconds the grinding of machinery and metal wheels began again and so too did the delighted shrieking of the people.

‘When Willer was shot he collapsed back into his cabinet, and his body remained out of sight in what the police called a basement.’

‘So it’s just a hole, a cavity,’ I said.

‘A hiding place designed for a vanishing illusion. But using it triggered the lock to the building, which is why the killer was trapped inside.’

Spoder took a few steps experimentally. He limped exaggeratedly at first, but it was clear he had not been seriously hurt.

‘I dropped the file, sir,’ Spoder said. ‘I think it must be down there inside the cavity.’

‘Are you going to go back for it?’

‘Not ever! I can download the files again if I have to.’