Keyhole

Exploration Stage: Secret Room
From: Cardsharp
Description: Another piece of the map was stolen. More than a century ago, a legendary thief lived in the City. You’ll never guess what his hobby was. He loved making complex locks! Such an idealist! He copied the stolen piece of the map onto the last lock he made. Please help me find it.
Completed: I can’t believe I’m holding that very lock in my hands... And there is the engraving of the map, nice! Do you know how the thief’s story ended? He created this lock, failed to open it, and was so disappointed in his craft that he abandoned it and became a pastry chef.