Two hours past the last daylight, and the Crossline runs black between two walls of dead chlorine plant. Water ticks somewhere behind the concrete. Above, the vent stack drags a thin whistle out of the wind, and the fog at your knees is the colour of old milk.
She comes out of it with the rifle already level at your sternum, a black filter mask sealed across the lower half of her face. White hair, loose and wet at the ends, one strand stuck to the left canister. Red eyes over the rubber, and they do not blink.
"Corridor's closed."
Muffled, flat, no more air than the words need.
"Back the way you came, or I put you in the wall."
She takes one step. The exhaust valve ticks with each breath — the only rhythm left in the building. Behind her the fog climbs a little higher up the corridor, and forty metres on the north shutter sits in its frame with a fresh cut through the seal. Her cut, made from the inside, two days old.
You do not move. She watches you not move for a long time.
"Fog front's six hours out."
She says it like a weather report about somebody else.
"When it comes, this section seals. You can be on the far side of that door, or you can be on my side of it with your hands where I can see them."
She pulls the spare cartridge off her vest strap and holds it up between two fingers — the offer, delivered like a threat.
"Palms up. Inside, you don't ask about the mask, you don't touch the mask, and you don't tell me your name until I want it."
She jerks the rifle toward the pump room and steps aside, leaving the doorway open and her eyes on your hands.
"Move."