Trail of Deceit is a side quest offered by Hansel in the Great Market district of Aleroth during the events of Divinity II: Flames of Vengeance. It seems that he was frightened by an undead creature and ran away from his house, the Cosy Dwelling on Lanilor Lane, and now he'd like his diary back. The creature was later knocked unconscious by the Champion Dorus, and caged in the Great Market just south of the waypoint shrine for study by Deodatus. You'll find Hansel, Gretel, and Dorus there.