Shaft 37

“Cooling water,” Daniel said, his eyes shut tight. “And an old ventilation line that runs to the subway maintenance level behind the hospital. People outside find out, they’ll come for it.” Marcus was about to ask more when someone knocked lightly on the door. Not the loose, unthinking tap of a patient. Three precise knocks. A pause. Then two more. All four of them went still. On the second round, the handle began to turn. Erin grabbed a metal supply cart. Lin backed up half a step. Marcus lifted the extinguisher in both hands. The person outside did not try to force the door immediately. Instead a calm voice came through the wood: “We’re here to retrieve emergency records. Open up. Everyone can live.” It was almost polite.