After failing a history test, Bart strikes a deal with Martin Prince to make him cool in exchange for tutoring. Bart successfully transforms Martin into a regular kid, but Martin reneges on his side of the bargain and Bart is once again in danger of failing. After an all-night study session, Bart still fails but he manages to impress Mrs. Krabappel with his grasp of history and she gives him a D-minus, a grade Homer is proud to hang on the fridge.