For the clue scroll: Go to the village being attacked by trolls, and search the drawers in one of the houses. Go to Dunstan's house in Burthorpe and search the drawers: "Wait till I get my hands on Penda, he's nicked the key again." Go to Penda's house, found in the bar kill him to get the key. Go back to Dunstan's house and open the drawer with the key in inventory. The key disappears and you obtain another clue scroll or a reward.