The corridor stretched ahead of them like the throat of something ancient—narrow, cold, washed in a faint blue glow that made the air feel submerged beneath an invisible ocean. Every breath echoed. Every step rang out like a warning.

Justina and Carson moved slowly, instinctively quiet, though the alarms behind them had stopped.

Too suddenly.

“Carson…” Justina whispered, her voice barely a thread, “why did the alarms cut off?”

Carson didn’t answer right away. He lifted his ...