As the door closes behind them, the stairs door at the other end of the hallway flies open. Brianna emerges, one arm hanging limp below the hastily bandaged wound in her shoulder.

"Emma?" She coughs on the sharp smoke.

The alarms may not be working, but the smoke detectors themselves finally are: the sprinklers in the hallway ceiling flick on, one after another. Brianna lifts her good hand to shield her eyes from the water and calls again, her voice scaling up in dread. "Emma?"