They found the key, while sorting through their grandfathers possessions. The key was an old fashion key, that would not have been out-of-place during medieval times. The skeleton key seemed to match up with the large antique chest that rested upstairs in the guest room.
A day late, but I present yesterdays 130 word prompt. Completed in a style of 50 word or less drabble. Let me know what you think down in the comment section.