In 1194, Pinky and the Brain are being kept in Merlin's laboratory in Camelot. When Merlin goes out for a snack. Brain tries to take over the world using a magic spell. Pinky gathers all the components but loses a dragon's toenail. Pinky and the Brain must go on a quest to get another toenail. Using a magic wand the recover the toenail, but the dragon chases them all the way back to Camelot. Brain uses the dragon's toenail in the spell but as he recites it Pinky distracts him. Brain's head is turned into cheese.
