You search the cabin top to bottom, searching for keys, real or otherwise, and anything that could hint to the mystery only you are aware of. The only other out of place thing you find is the anvil in the corner, mysteriously out of place, atop which is... another shitty drawing of a key. God dammit, who's making these? You start to feel an insoluble sense of rage at this mysterious key perpetrator, but there's no finding them unless you can leave the cabin. No one else is in here but you, that much you're aware of.