The low-level skirmish between Paradise and Regent’s Park had formed a fluid front-line ahead of them. Stray shots from that battle clattered overhead: sometimes a rooftile or a window would crack and fall in pieces to shower the street below.

Petrovitch’s back rattled against the metal screens. “Aren’t we going the wrong way?”

“We have to go this way to go back. Is that okay?”

“Since any answer other than yes will get my limbs torn off: yes.”

She grinned, and the whole of her face lit up; no longer the avenging angel, but the teenager out on her first date.

“Down here,” she indicated with a jerk of her head, and cut into a gloomy street beside the station. On one side was a terrace of pre-Armageddon, probably pre-Patriotic War, houses. They faced a battered chain-link fence that separated the road from the railway tracks, and soon she found a weakness in it.

She dragged the base of the wire up, straining at it with her clawed hands. A shower of soil and weeds and litter fell from its mesh. Petrovitch took his cue, and rolled underneath, picking up mud on his coat. She followed, after making the hole bigger.

They slipped and scrabbled hand in hand down the embankment and onto the oily ballast beside the rails.

“Watch your step,” she warned.

“Kind of figured that.” He looked back in the dark mouth of the station. The platforms were immense, jutting out from under the covered section and into the distance. He tried to imagine the number of carriages it could have served, thousands of people at a time coming from outside the city and spewed out right there, one train after another, every few minutes. “Listen.”

The overhead power lines, supported by spidery metal gantries, were humming.

“I thought you said nothing was working?” She stared up the empty line. It passed under two bridges before disappearing into a tunnel.

“I think I said we weren’t in control of anything; a world of difference.”

“We need to go that way.” She pointed down the track, away from the station. “If there’s anything you want to tell me, now’s a good time.”

Out of sight, a steel wheel screeched. The ringing, whistling noise echoed around them. Petrovitch licked his dry lips and remembered the cars. “Have you got another plan?”

“It’s not as good.” She turned to see a train, lights as bright as stars, wink into existence. The slanted face of the power unit grew, framed by the road bridge it had to pass under. “Is this something to be afraid of?”

“Yeah.” He started edging back toward the wire fence.

Her hand curled around his arm. “Wait. We don’t know which way to run.”