I asked because I could smell burning – the acrid smell of an electrical fire, melting copper, blistering insulation. We must be surrounded by equipment handling the Underground’s canalised lighting, all of it out of warranty, overdue for replacement, caked in dust. I had seen it in documentaries. The men who went into the tunnels at night. The Tube acts as a giant vacuum cleaner, sucking human detritus from the light into the darkness. I could see those documentaries again, now, in my mind’s eye: a gloved hand bringing up a smoking grey fistful from the ballast around the tracks, like a robot submersible on the ocean bed. This accreted dust and hair burned very well.

‘I can’t smell anything,’ Alan said.

He was wrong, surely. Though it did not seem to be stronger, I felt that the smell had become inescapable; perhaps because I was more focused on it, it had begun to block out all other sensations, almost as if it were welling up within me, a toxic spasm in the lungs rather than a scorched and poisoned breath from the tunnel.

I looked about to see if anyone else had smelled fire, expecting others on the platform to raise their heads, frown, sniff the air – the herd detecting danger, abandoning their quiet little worlds of phone and newspaper to confront an environment that had become unsafe. But no one raised their eyes, no one even stirred. Couldn’t they sense it too? How could they all be so oblivious?

The breeze from the tunnel grew stronger, and I could see it now, see the smoke, a steadily thickening haze carried on the back of the column of air pushed out by the approaching train. And I could feel it on my skin, in my eyes, hot and stinging. I raised my hand to my face and did not lower it. I was hot to the touch. I coughed, and fell into a fit of coughing, unable to stop. Hair and skin, on fire in the darkness, one of those coal seam fires that burn for decades, inextinguishable, slow death to the communities above. I felt ready to vomit.

‘You OK, mate?’

Alan was scowling at me, but not without kindness. I barely registered his expression, though; behind him, the sealed panels looked about ready to start jetting smoke, opaque and heavy yellow-stained smoke, any second it would begin.

‘We’ve got to get out of here,’ I said, barely able to speak, each word displacing more poison into my lungs.

‘What? Train’ll be here in a second.’

A second was too late. The air was going, it was gone, no way to get at it. Suck it in and the poison would come too, into the blood, into the brain. Then the light. It was almost too late. I needed cold air, cold water on my face, coldness in my throat.

‘I’m sorry,’ I said. And I ran.

THREE