They walk on, and on and on, and then on a ways more. The pools on the tunnel floor dwindle. The dripping fades into silence. A big jagged hole appears in the tunnel wall, like something as tough as a troll punched a hole through the bricks. The passage on the other side of that hole is narrow and ends at a metal grating. Minx pushes the grating open and they step into another tunnel, big and squarish, with tracks, like tracks for subway trains.