Once inside immediately find the Landmark to establish dominance then check the pile of bones. In the next room you are ambushed from three sides so work one side at a time to overcome this. At the southern end is a pile of bones and a door to the next area, currently locked. Head north and defeat the Key Master to receive the Key . Check the chest in the northern area and in the southern is another containing The Sorrows of Arlathan . Open the locked door and defeat more Shriek Alphas and loot the rubble. Unlock the final door and examine the shard to update the quest. Leave and head to the Cadash Thaig.