After the company killed Shunn Shurreth's Drider. Shunn convinced the party to seek out the wererats for a small reward of 50 gold. Shunn tells the party that the wererats stole a key from him but he doesn't know what the key goes to. Shunn found the key on this level of the dungeon.
The characters backtrack and head south and decide to take a rest after finding an old storage area for Dwarven tools at the end of a small tunnel.