This area must be explored in order to complete the achievement Nooks and Crannies. This area has no related quests.
Upon entering, a man calls for help. The guards turn into monsters that you have to kill. Once they're dead the man opens a gate and allows you to keep the contents of two chests claiming, "I'm not the fighter my father was." Judging by the contents of the chests, his father wasn't much of a fighter either.