Panic catapults me from the seat and I lurch across the aisle. I skid next to her, drop to my knees and haul her up into my arms. Her body is limp, beads of sweat on her forehead and her hair, damp in my hands. I feel her wrist, a faint pulse.

She opens her eyes and looks at me.

“Bea? Oh god. Bea!”

She blinks at me. Turns her head from side to side, a look of bewilderment on her face. “What happened?”

“You’re OK,” I tell her. “We’re all right.”

But then I look around.

The other passengers—the old woman, the tourists, the sweaty man in the shorts, all of them—they’re not moving. Not moving at all.

They’re frozen.

“Stay here,” I tell Bea, resting her head gently on the floor. “I’ll be right back.”

She nods, bleary-eyed, and mumbles something.

I leave her and I walk down the carriage, accompanied by the loud squeaking of my Stan Smiths. My head throbs. I stand in front of the old woman. She doesn’t move. I wave my hand in her face. No reaction. It’s like she’s been turned into a Madame Tussauds wax model. I try the tourists. Same thing. The man in the shorts. No response. Not even an eye twitch.

OK, it’s official, I’m freaking out. “Bea,” I yell. “The hell’s going on?”

She doesn’t answer.

The lights flicker, then go out entirely.

The carriage is plunged into darkness.

I see nothing. Then silhouettes. Pale faces.

The lights snap back on. I look at Bea in panic. She raises her head, stares at me strangely.

“You OK?” I shout.

She waves her hand at me. OK, she mouths back.

I walk on to the sliding doors of the carriage. In the glass lies my reflection and a wall of foreboding darkness. We’ve stopped between stations. I try the door button. Nothing happens.

“HELLO!” I shout.

No answer. I look at Bea again. She’s sitting upright now, rubbing her head.

“HELLO!” I pound the door with my fist. “Is there anybody out there?”

Silence.

Which makes sense. We’re in the middle of a tunnel.

The loudspeaker crackles and hisses. I wait for the driver’s voice and nothing comes.

I’m on the verge of yelling out again, when the carriage lurches and I’m thrown backward. We’re on the move. I plant my feet as we gather speed. I look back at Bea.

“Hey, Bea!” I yell. “Just hold on, OK? I’m coming.”

But we’re moving at pace now—fast—and I’m struggling to stay upright, let alone get back to her. I shouldn’t have left her.

My heart jackhammers. “It’s OK!” I shout. “I’m coming. It’s fine.”

I’m wrong. It isn’t fine.

We pull into a station and the train slams to a stop.

But I can’t move.