The red heat outside grew and grew. The paint on the door began to blister. Stanislav pulled his sleeves over his hands, gripped the door handle firmly, and bellowed his defiance.

The door banged against the jambs, and still the paint bloomed and puckered. Dalip thought he was going to die there, watching the door burst into flame, waiting for the wall of heat to ride over him, his clothes igniting, his hair turning to brief, bright lights and his turban a fiery crown. He would wear the same silent expression of sudden, violent death as the rest of the work crew had done, his mouth making momentarily a hollow circle before his flesh scorched and his muscles grew rictus tight.

He scrabbled back as far as he could go, until he realised he was against another door, and it was cold metal.

He leapt up, pulled the handle. The door opened easily and cleanly. It was dark on the other side, but that didn’t matter for the moment.

‘In here,’ he said, just as the paint blisters burst with blue fire. Stanislav pushed past, and Dalip closed the door smartly behind him.

Stanislav slumped against the wall and coughed until he vomited, turning his head at the last moment to splatter the ground with acid bile.

Dalip’s eyes burned from the fumes and the heat. His throat was raw, his head hurt, his skin was sore and he couldn’t stop shaking.

The others had died, right in front of him, lighting up and lurching around on the rail track until they fell. He felt his own stomach tighten, and he tried to swallow, but he was parched.

‘Where are we?’ he managed. He fumbled for his torch and tried to make sense of the discordant images he was seeing. Two more doors. A series of grey cases and switching gear, also grey.

‘Down Street.’ Stanislav wiped his mouth with his hand. ‘Disused station.’

‘We must have gone past it the first time.’ Dalip tried the door in the long wall; all that lay beyond was a rusted bath tub, no taps.

‘There is no one here. No one to get help from. That is why we went to Green Park.’

‘The others. They’re—’

‘Dead. Yes.’ Stanislav pulled himself upright on the painted switch-gear. ‘You saw them. They could not have lived. We must work hard not to join them.’