There is a key, under the doormat. You can see it, because the doormat is not solid. You are meant to find it; it is a trap. Pick it up anyway. Open the door. Every trap guards treasure.
Behind the door, a small room. Filling the room, bees. Just, so many bees. Do not worry about the bees; they will not leave the room. Let them worry about you. Do not think about the bees. There are so many bees. Also teeth. In a pile. Surrounded by bees.
There are a lot of teeth. Not too many teeth. Not as many teeth as there are bees, but more teeth than a human should contain, despite these being human teeth. Gently sift through the teeth until you find three stone goblets.
One of the goblets perfectly holds a human amount of teeth. You must quickly identify it, and fill it. Do not remove the other two goblets. Do not acknowledge them. Fill only your goblet with teeth. Then pour the teeth into the mannequin. The one that has always been there. The one with the jagged hole cut into its face. Hold the goblet under its chin. Wait. The goblet will slowly fill with blood.
When the goblet becomes full, immediately drink the blood. Do not spill the blood. Drink it quickly. Do not spill. The blood will protect you from the bees. You may now take the treasure, as well as the remaining teeth. The key is no longer of concern, you may leave it with the bees. Do not acknowledge the other goblets. Gently close the door when you exit.