The gap is barely wide enough for shoulders, but the protagonist goes through headfirst — broom still clutched, habit overriding sense. Inside, the dark is not quite dark. Walls of pale mycelium pulse with moss-green light, fine as lace and faintly wet, branching and rebranching into depths that should not fit inside something no wider than a church door. The hum resolves here. It is not syllables exactly, but it is patterned — a rhythm the protagonist recognises the way you recognise a heartbeat you have been hearing for hours without knowing it. The air is warm and close, tasting of copper and something sweeter: the kind of sweet that catches in the throat. Behind, through the narrowing gap, the guard's voice cuts off mid-order. The mycelium is already threading the entrance shut, fine white filaments lacing across the light. The green glow waits ahead.