[Finlay and Fandir]
It's only a short journey to the breathing hole, but Klaus feels deeply uncomfortable - the smell, the darkness and the feeling of constriction are overpowering. Julian is more at home in tunnels, but even he is disgusted by the stench. The system hasn't been very well maintained by its human owners.
Klaus's lantern happens to illuminate a dry pipe in the wall to his left, and dozens of tiny eyes stare back at him. It's full of rats!
He cries out in alarm and almost drops the lantern. The noise makes the rats retreat further into the pipe. After a moment, Klaus collects himself and they continue.
Further on, they discover a wooden door built into the stonework (S2 on the map). Julian is very surprised to see this, since it isn't shown on the map and anyway has no reason to be here. He notices that the stonework has been crudely hacked away in order to install the door, which itself is very badly made. Klaus notices a strange sign carved into the stone beside the door, but he has no idea what it means. Julian is sure that the sign is not dwarfish.
They carry on to the breathing hole (S1 on the map), knowing that the passage is a dead end and they will have to pass the door again anyway. The shaft the goblin entered by is very narrow - only 12" square, and it's amazing that the goblin was able to fit through. There should have been an iron grill at this end of the shaft too, but it has rusted away to almost nothing. Klaus studies the opening closely, and notices traces of greenish blood. The blood is not only on the remains of the grill: it runs up the breathing shaft, and also continues down the sewer passage he and Julian had just walked down.
Now that they are aware of the blood trail, they should be able to follow it without too much trouble, provided they go slowly and search with care. The trail runs on the other side of the passage to the mysterious door - but are they interested in opening it anyway?