The Key to Solving the Mystery

Exploration Stage: Knowledge Archive
From: Eleanor
Description: It seems Martha saw a flying key in her vision. She believes it’s connected to the sender of the message. But even if there is such a key in the Library of Knowledge, where could it be? Could you look around for it?
Completed: It looks like a key created by an inventor so that even if it were lost, it would find its way back to its owner. However, it seems the invention was a failure. This probably isn't what Martha is looking for.