I grin. I’m enjoying myself. Farah Rafiq is telling me a cool – OK, slightly weird – story and I’m cracking jokes. I fantasized about having this level of conversation with her a thousand times and now here I am.

“Sorry. Go on,” I say.

“They begin to study the shadows, make up rules to predict what kind of shadow will appear next. When a prisoner gets it right they’re praised by the others. They call them: master.”

“OK, I get it,” I say. “It’s an analogy. The prisoners are doing what scientists do: looking for patterns, trying to guess at the nature of reality. And some of them guess right and so everyone looks up to them.”

Farah smiles. “Not just a pretty face.”

I like the way she smiles with her whole face, even her eyebrows.

“You don’t need to sound so surprised,” I say. “I want to do A-levels too. After my retakes.”

Farah nods shortly. I appreciate that she doesn’t feel the need to remind me that there probably won’t be retakes, or A-levels, or anything else now.

“One day, one of the prisoners escapes,” she continues. “They blunder out into the real world. Plato called it ‘the ordinary world’. And instead of seeing shadows, they see physical three-dimensional people for the first time.”

“That … would be scary,” I say.

“What do you think happens next?”

“They go all Ironman on them for locking everyone up? Blast the place to hell.”

Farah smiles thinly. “You’re not taking this seriously.”

“I am, I promise.”

“They go back into the cave and try to explain what they’ve seen. But nobody believes them. They think they’re a fool.”

I take a minute. “I see what you’re saying. Everything we’ve known until now, the thing we call reality, might not be the reality. It might just be shadows on the cave wall.”

“Right,” Farah says.

“But we’re still not really here, are we? In this corridor.” I gesture around us. “I’m still passed out on the street or in the back of an ambulance on the way to hospital. You’re probably on a ward too by now.”

Farah shakes her head. “You’re being too literal. The idea of you lying on the pavement in town is no more real than the idea of you and me sitting here. They’re both different representations of something else entirely.”

I think it through. “The thing we call ‘real’ is only the ‘real’ we’re most used to.”

“Exactly,” Farah says.

“You think we’ve stepped outside the cave, don’t you?”

“Outside, or into another one.”

We find a cupboard filled with bandages and dressings and we fashion elbow pads and helmets from them. We fight with mop handles, swinging wildly, making thick whapping sounds against each other’s paddings. We giggle so hard we can hardly stand and we fall into each other and stagger around like we’re drunk or delirious. I swing my mop back over my head and it catches a glass panel in the door behind me and the glass shatters, turning into an astonishing cloud of jagged light.

We fall silent, staring in disbelief at our destruction. Then Farah places her hand over her mouth and guffaws. My heart thuds in my ears and I can feel my pulse behind my eyes and I can’t help but feel guilty in spite of everything.

“Are you sure people in the ordinary world can’t see this?” I say.

“Pretty sure,” Farah says.

“How?”

“Think about it. We can’t be the only people this has happened to. There’s the guy in Casualty, the baby. I’ve seen a few others.”

“I guess.”

“You think you’re the first person to smash things up?”

“No.”

“Well then. It must be that they can’t see us. Or else the ordinary world would be full of poltergeists.” Farah frowns thoughtfully. “Are you hungry?”

“Not particularly,” I reply.

But we go in search of food anyway.

The canteen has a sad, deserted feel to it that probably isn’t that different to how it feels in the ordinary world. Moulded plastic chairs like in the waiting areas, a station with a shelf for sandwiches and a salad bar, some kind of heated counter, a windowed fridge, a rack with crisps and chocolate bars. I hope briefly that I’ll find a packet of Liquorice Allsorts … but no luck.

“No fresh food but they have sandwiches and chocolate bars,” Farah says.

“No people but chairs and buildings and beds,” I remark.

“It makes no sense.”

“It makes sense,” I say. “The rules are different, that’s all.”

We gather a stash of whatever food we can find and lay it out on the table between us.

I don’t remember the last time I ate. I should be ravenous. But I stare at the food with a sense of dismay.

“I don’t think our bodies need food here,” Farah says.

“No,” I agree.

She picks idly at a bag of crisps. “Have you had a dump since you got here?”

I’m caught off guard and I snort into my can of Coke. I collect myself. “Nope. I haven’t urinated either.”

Farah laughs now. “Oh, oh, right, you haven’t urinated?” She speaks in a haughty voice, waving her crisp in the air as she talks. “Have you been to the boudoir to powder your nose?”

“Shut up,” I mutter, smiling.

Farah turns more serious. “I think that might be another thing we don’t need here.”

“What?”