They come to another grating in the tunnel wall. Minx pulls it open. The passage beyond it is small and squarish. They have to bend forward to get through it. That leads them into a maze of passages, some large enough for them to stand upright, some so small they have to get down on hands and knees. Monk is in the process of deciding to ask another question when, abruptly, the tunnel they’re in comes to an end and Minx turns to face him.