Dominic groans as the train jolts to a sudden stop in the middle of a field, the immediate absence of purring engine giving way to tuts and sighs as the same realisation dawns on the few others in the carriage. I squint out of the window at the meadows around us, grass whipping with the wind, catching the distant roar of the A12. There’s no dip and roll to these fields. If we were still moving, we’d probably be no more than ten minutes out. Overhead, a loud pop ends the start of an announcement crackling from the speaker before it’s even begun. I wobble as I stand, moving into the aisle.

‘That’s not exactly a good sign, is it? I’ll go and see if I can find someone.’

Dominic swears as he gets up too, pushing past me out of the carriage.

‘You’ve got to be kidding,’ he snaps, scrabbling at the second set of doors ahead of us.

‘Isn’t there a button?’ I say, straining to see round him. ‘Sometimes you have to … ow!’ I shrink as he steps backward into me, looking up and round the doorframe.

‘They’re automatic. Aren’t they? Those ones were…’

We turn back to the doors we just came through, flat and gleaming like a closed window. I step so close to them that my forehead almost touches the glass. Did I float through them?

‘That’s impossible,’ I murmur, prodding the glass with my finger. ‘Did you have to push a button on the other side?’

‘Of course not. They just opened.’ Dominic kicks the glass. Nothing.

‘Try those again,’ I say, twisting back round to the other set. We 209push at them, Dominic swearing as he runs his finger down the groove in the centre.

‘This is absurd,’ he shouts, punching the glass and pacing the two steps back to the other doors. And just like that, we’re trapped in the lobby – exit door on either side, glass doors forming the rest of the box around us. And just like that, I realise I followed him without thinking twice about it.

I rest my head on the glass, staring at the bobble hat motionless on top of the seat in front of me. That was the warning and I missed it. That woman and her baby, immediately knocked out by his cocktail of kindness, attention and understanding. I should have known then. I should have remembered immunity can never be guaranteed.

‘Try those again,’ I say, twisting back round to the other set. This can’t be happening … trusting Dominic? I watch as he pushes at them, swearing, running his finger down the groove in the centre.