The Grundlekrunk's Lair

The group passes along into the mine, deep down into the depths of forgotten bloody metal. Sunlight disappears as the group descends, giving into darkness... With burned out torches and broken lamps around, it's rather dark. There are a few torches lit though. So, there's some illumination. The deeper the party goes, the more the stench of death and rot is evident. Soon the group will come to a large cave. The deepest spot in the mine. Inside the cave is a large pit, littered with at least fifty dead or half-eaten me and women.

There seems to be no monster inside. What do you do?