On a sunny day in Springfield, Bart is not excited about going to school; in part because he has to travel there on a prison bus, sit in new chairs that are very uncomfortable; and even more so when Ms. Krabappel informs the class that they will spend two hours longer than usual at school that day (due to Bart tampering with the clock). When arriving at school, Bart forges a note claiming a dentist appointment so that he can skip school, but Principal Skinner is not convinced. Skinner chases Bart through Springfield, and as he finally corners him, Bart jumps into a passing car. The car is driven by Freddy Quimby, nephew of Mayor Quimby, who is going to his birthday party at the Quimby Compound, which Bart crashes, claiming to be Mayor Quimbys nephew "Bart-Bart". At lunch, Freddy is served chowder, but he ridicules the waiter for mispronouncing it in a French accent, even though Freddy himself mispronounces it with a Boston accent. He then follows the waiter into the kitchen, and apparently roughs him up. Bart, hiding under a table, secretly witnesses the true turn of events. Freddy is charged with the crime, presumably assault and battery, and is put on trial.
During the trial, despite Quimby's attempts to rig the trial, the whole town seems to believe that Freddy is guilty due to his demeaning behavior and intolerance of how every person around him says "chowder"; he even threatens to kill his own lawyer and the jury for it. Only Bart knows otherwise, and he confesses to Lisa that he's the only one who knows that Freddy didn't actually assault the waiter. He doesn't want to testify, however, because the only way Bart can confirm that Freddy is innocent is by admitting that he skipped school, and thus would face punishment from Skinner. At the trial, the jury consists of Homer, Skinner, Hans Moleman, Ned Flanders, Helen Lovejoy, Jasper, Patty, Apu, and Akira.
Homer votes against the others because he wants to create a deadlock so that the jury is sequestered at a hotel with free room service and cable television. In court, Lisa convinces Bart to testify, and Bart tells everyone that Freddy did not assault the waiter, but that the waiter injured himself in a series of clumsy actions. The offended waiter attempts to deny that he is clumsy, but in the process, he trips over a chair which causes him to fall out of the window into an open-roof truck filled with rat traps, thus proving the point. Freddy is cleared of all charges, and Skinner, although praising Bart for being honest and coming forward, reminds him that this does not change the fact that he skipped school.
Despite Bart's logical argument that his act of selflessness nullifies his misbehavior and that leaving him in peace would be the fairest thing to do, Skinner is unmoved and not only proceeds to coldly give Bart three months in detention, but then increases his punishment to four months for nothing more than the pride of annoying Bart. At night Marge tries to talk to Homer about the things he missed at home but he continuously tries to fool her with his fake eyeglasses. However, Marge sees past this and Homer finally admits to missing being at home with her.