You lift the rusted hatch and drop into the darkness below, boots landing with a wet squelch on the damp concrete floor. The air is thick with mildew and old oil, stale from years of disuse. You crouch low and begin crawling through the narrow maintenance tunnel, your breath echoing off the walls as the space tightens around you. Pipes rattle above like bones in a cage, and the occasional drip of water becomes a steady metronome to your heartbeat. Every scuff of your boots feels too loud, too sharp — and somewhere above, something paces, its claws tapping lightly on the metal grates.