Abi comes over and sits on the far side of Farah, her face a mixture of scepticism and hopefulness. “It’s possible. Anything is possible in this god-forsaken place.”

“Surgical removal?” Vikram remarks, impressed. “Why didn’t we think of that?”

“We lost Alistair to hyperdactyly,” Marcus explains.

Farah withdraws her hand and wraps it again. “What are you all doing here?” she says. “You said you were studying … disconnected…?”

“Disconnected consciousness,” Vikram says.

“This is our lab, in the … real world,” Benedict continues. “We’ve been studying the nature of consciousness for many years now.” He sips his tea and watches us intently. “We discovered that in certain circumstances, patients who appear unconscious sometimes display neurological activity that’s indistinguishable from that of somebody who is fully conscious. We believed – and now we know – that it signifies a new state of consciousness.”

“Not dreaming, not hallucinating. Just … not there,” Vikram says.

“You mean here, in this world,” Chiu says.

“Exactly,” Vikram says.

Chiu nods excitedly. “I read the journal article.”

“Our biggest breakthrough was when we discovered that people in this state could communicate with each other,” Benedict explains. “We ran a study with twins who had epilepsy. One pair in particular, their seizures always happened at the same time and they were able to pass messages to each other while they were, supposedly, unconscious.”

“How do you know?” Chiu asks.

“They would tell us when they woke up.” Benedict smiles. “Ask one of them to think of a secret word, over and over. Think it, but don’t share it unless and until you realize that you’re in a seizure. Then they would come back and the other would know the word.”

“It’s like a radio,” Vikram adds. “Everyone you’ve ever known is tuned to Radio One. But sometimes, like right now, we’re all tuned to Radio Two.”

“That still doesn’t explain how you’re all here,” Farah says. “It means you’re all unconscious in the ordinary world, right? Like … was there an accident or something?”

Benedict’s mouth pinches, he seems uneasy.

Vikram answers for him. “It was all theoretical. Naturally, we needed to test our hypotheses under experimental conditions.”

“Which means?” Farah says.

“Medically induced coma,” Marcus says.

Farah looks shocked. The scientists shuffle awkwardly.

“You did this to yourselves?” I say, incredulous.

“Officially this is a sleep study,” Benedict explains. “But we’re not really sleeping, we’re sedated, in the beds you will have seen in the sleep lab next door.”

“That can’t be legal,” Farah says.

Abi exhales: a short, bitter note.

I look around at the trashed room, the car batteries that power the kettle and the CCTV. I think about the seven beds for four people. “Something went wrong, didn’t it?”

“It went wrong from the moment we arrived,” Abi says.

“How?”

“Our plan was to spend two weeks here,” Benedict says. “Enough time to record our observations and establish communication with the ordinary world.”

“We lost Alistair to hyperdactyly right away,” Abi says. “We presume he reacted badly to the anaesthetic.”

“Reacted badly to the anaesthetic in the ordinary world or slipped through the cracks in this one,” Vikram muses. “Depending on which way you look at it.”

“Either way, he died in a few hours,” Abi says.

“We were attacked a few days after that,” Marcus says. “We were idiots and left the lights on. It seems that some people arrive here and get together, form gangs. Of course, we didn’t know that at the time.”

“They killed our colleague Jessica, and took Eduardo,” Abi says. “But we killed one of theirs in return and managed to drive them off.”

“After that we got serious,” Marcus says. “We armed ourselves. Built the airlock. Benedict and I got the security camera working. We’ve rigged the place so if they try again, we’re ready for them.”

“How long have you been here?” I ask.

“Two and a half years,” Abi replies. “Our best guess, anyway.”

I take a breath, understanding at last the unspoken tension in the room. Abi’s eyes, I see now, are tight, tired and angry. But there’s still something they’re not telling us.

“Why haven’t you gone back?” I say. “If some of you were dying, why didn’t your colleagues revive you in the ordinary world?”

“Natural occurrence of this brain state is very rare,” Benedict says. “But we used a cocktail of medication and deep-brain stimulation to trigger it in ourselves. You’re right, our colleagues in the ordinary world should have revived us by now. Our best guess is that being here is preventing them from reviving us in the ordinary world.”

Chiu flashes me a brief, triumphant look. “That’s what the machine was for, wasn’t it?” he says. “If reviving you in the ordinary world didn’t work, it was meant to get you back from this side…?”

He trails off, his voice pinched with the fear of disappointment.

Farah places a hand on his shoulder. “We thought the machine might get us back?”

“That is what it’s designed for. But I’m afraid it’s not so simple,” Benedict says. “Our plan was to establish communication with the ordinary world, modulate our cytoelectric impulses and use our brains as aerials. But our maths was off. We hoped that the machine would provide a route back if our colleagues couldn’t revive us. But without being able to talk to them we have no way to know if the machine is safe.”

“We had no way to know,” Abi corrects him. “We have new evidence now.” She picks up Chiu’s paper and quotes from it: “ ‘The team successfully manipulated the cytoelectric activity of a coma patient, restoring them to wakefulness.’ That’s Devon, right?”

“It’s possible,” Benedict says. “It’s not certain.”

Abi looks incensed. “Not certain?”

Benedict turns back to us, ignoring Abi’s challenge. “When our communication failed, we agreed not to use the machine until we’d further developed our theories. That’s what we’ve been doing these past two years: trying to understand where we went wrong and establish whether or not the machine is safe.”

“We did use it once though,” Vikram says. “Our colleague Devon was badly injured when we were attacked. He was dying, so we took a chance and used the machine.”

“And—” Chiu says.

Vikram shrugs. “And … he disappeared. We have no way of knowing whether we helped him back to the ordinary world or helped to finish him off.”