When Bart tries to get Lisa to stop practicing her saxaphone, he gets in a struggle with her that results in the instrument flying out her bedroom window and onto the street. The sax is instantly flattened by oncoming traffic. Crushed by the loss, Lisa is cosoled by Homer, who tells her the dstory of how she got her saxophone.

The story revolves around Bart's adjustment to school. He has difficulty fitting in and becomes depressed. Homer and Marge bring little Lisa with them when they meet with the school psychologist, Dr. J. Loren Pryor, to discuss Bart's problem. Though he offers little advice for Bart's situation, he discovers Lisa is gifted and encourages the Simpsons to nuture her talents.

The Simpsons can't afford to send her to a private school, so they look for another outlet to foster Lisa's gift. Meanwhile, Springfield is suffering through the hottest summer on record. Bart discovers he's good at making people laugh at school and decides to become a class clown. Homer decides to forgo the air conditioner he planned to buy and instead purchases a sax for Lisa.

After finishing his storyHomer is told by Margeto use the money in the current air-conditioner fund to buy Lisa another sax. He does.