98‘Did you hear that noise my mum made?’ Karim says. He’s pale and sweating. ‘She sounded like a fudging monster.’

‘Like a Demogorgon,’ I say, my brain catching at something. A chance. ‘Guys, come and help me move this stuff.’

We run to the shelves of supplies – Kat and Karim taking one end, while I grab the other.

‘On three,’ I say. ‘One, two, three.’ And we pull. The shelves are heavy, and the stuff on them even heavier, but we heave as hard as we can. They rock forward slightly, and then the weight of the water bottles takes over the momentum and the whole lot topples forward, crashing onto the ground. In the wall where the shelves had stood, is a door.

‘Concealed exit,’ I say, jumping towards it and pulling down the bar. ‘There had to be one.’

‘Legend,’ Karim says, jumping over a water bottle as I push the door open.

‘Wait,’ Kat says. ‘Everyone grab a bottle. We can use them to block the door.’

It takes a few seconds, but on balance I think it will buy us more time than it costs, so we pile up a load of stuff against the door, jamming it in as 99 well as we can so that it will be difficult to move. And then we run.

We sprint up the tunnel faster than the lights can turn on, so I almost crash face first into the wall that suddenly looms up in the gloom in front of me. I put my arms up to take the brunt of the impact and grit my teeth as they hit metal rungs.

‘Ladder!’ I say. ‘Kat, you first.’

She’s up and off like a squirrel. I shove Karim after her and I take the rear, getting a view of Karim’s butt that I never really needed in my life. Lights flicker on as we climb, but for a long time I can’t see an end to the ladder. The climbing is hard going. My arms and shoulders are burning with the strain of pulling myself up each rung, and my legs are threatening to go full jelly. Karim is slowing, and I don’t blame him, but we need to be out of here before whoever is chasing us gets within spitting distance if we’re going to have a chance of getting away without being identified.

‘You’re nearly at the top,’ Kat calls down after forever. ‘Just another few metres. There’s a hatch.’