Bodies had caught down the sides of the chute, so that the length of it was lined with the detritus of the dead. There were no footholds except upturned skulls; no handholds except the unreliable levers of femurs. A ribcage jutted out here; a scapula there. Looking up and seeing the bones cascading down in frozen motion was like seeing a freeze-frame of being sucked into hell.

‘I’ll have to remind Grumpy Jock to add this to selection,’ I said under my breath. And then aloud, as I worked my way out again, ‘There was one thing you did forget, Baaz.’

‘What’s that?’

‘I’m nearly twice your size.’

‘Oh,’ he said, at first dumbfounded and then dejected. ‘Oh no. Can we do it?’

‘No idea,’ I said truthfully. ‘Can’t see the top. It curves around after four metres or so. Maybe I’ll get through, maybe not. You’re going first, anyway.’ He looked at me, nervous, left hand drumming away at the air again. ‘You have to. I can get through what I’ve seen, but I’ll bring everything I brush past crashing down as I go.’ He reached for the torch. I held it back. ‘It’s better you don’t see what you’re holding on to.’ He wriggled his way into the hole, coughing and swearing in Punjabi as he went. I held on to his ankle to slow him down, and bent round so he could hear me better. ‘Baaz?’

‘What?’

‘Two things. First – if we get separated, don’t go straight home, and definitely don’t go to the cops.’

‘OK. And what’s the second thing?’

‘This was your idea.’

I let go of his ankle and slapped his calf through his wellingtons and he vanished up the chute – the fine shower of bone splinters that fell back into the cavern the only trace anyone was up there at all. I turned around to do a final sweep of the chamber. I slung the M4 tight to my chest and killed the torch. I waited for Baaz to get a couple of metres ahead of me, and then forced my weight up behind him, pulling myself up the rungs of the bone ladder one femur at a time, snaking my way through the shaft.