Never say never

Exploration Stage: Mansion by the Canal
From: Never say never
Description: If you agree to descend into the Dungeons and save the lost girl, I will show you the key's hiding place. Quid pro quo. agree? Good, then listen. The cache is in the Dungeons under the Chest but you can only open it if you have a magical threefold amulet. If you put an amulet close to the cache, it starts glowing. But where to find this amulet I do not know.
Completed: I've kept my word and pointed you to the key's location. Now you keep your and save the girl who cries for help from the depths of the dungeons.