As they drive through Springfield, Bart and Lisa grow suspicious when Marge and Homer treat them exceptionally nice. Moments later Homer hits some buttons, causing the car door to lock and the windows to shut. The car pulls into a medical plaza, where Dr. Hibbert greets them with a chuckle and a syringe. Bart and Lisa realize it’s “shot day.” Lisa summons her courage and gets the shot over with, but Bart won’t give in so easily. He grabs some lollipops and hops out an open window. Hibbert pursues Bart, but time after time the boy outsmarts him. A defeated Hibbert slumps on the curb in front of the Simpson house. Bart tries cheering him up, but moment later “Hibbert” pulls off his mask, revealing Barney underneath. Barney grabs Bart, and Hibbert jabs Bart in the stomach with a needle. Before long Bart realizes he’s lost his hearing. Hibbert assures the family it’s merely a side effect of the shot, and the boy’s hearing should clear up in a day. Hibbert tricks Homer into signing a malpractice waiver, then runs off. Marge tells Bart he can stay home from school, but Bart wants to go so he can see the donkey basketball game, which pits students against teachers. The following evening the students and teachers warm up in the gymnasium, which is packed with people from throughout Springfield. Before the games begin, a giant American flag unfurls from the rafters, and the national anthem plays. Bart doesn’t see the flag behind him, nor does he hear the anthem because of his deafness. He teases one of the donkeys by shaking his rear-end at him. The animal chomps on his pants, pulling them away. The crowd gasps, mistakenly believing that Bart is deliberately mooning the American flag.

Homer and Marge meet with Principal Skinner to discuss what happened. Marge insists Bart didn’t know what he was doing because he was suffering from temporary deafness. Meanwhile Bart’s hearing comes back. When he goes to school, the other kids, believing he’s unpatriotic, beat him up. The news media picks up the story, and before long photos of Bart mooning the flag are everywhere. The entire town of Springfield turns against the family. The Simpsons receive an offer to tell their story on Hardball, hosted by Chris Matthews. Matthews twists Marge’s words, and before long a flustered and angry Marge blurts out that she hates Americans, and insists the town of Springfield feels the same way. It isn’t long before the entire country turns against Springfield. In an effort to save the town, Mayor Quimby changes Springfield’s name to Libertyville. When Homer enters the bar to drink and hang out, his friends desert him. When the Simpsons show up for church, the choir members pull off their robes and reveal they’re all S.W.A.T. team members.

The Simpsons are taken to prison, where they’re charged with high treason. Among the other detainees are Susan Sarandon, Tim Robbins, Sean Penn, Janeane Garofalo, Michael Moore, the Dixie Chicks, and Bill Clinton. After her family is drugged and interrogated, Marge tells Homer they’ve got to find a way out of prison. An old coot tells the family the best way to escape is during the prison talent show the following evening. As the talent show gets underway, the old coot tells the family to make their break at the end of their act. The Simpsons take his advice, and after a song-and-dance number, they disappear through a passageway. When they exit the tunnel, they realize they’re trapped on Alcatraz Island. As the family swims for shore, they’re picked up by a passing foreign fishing boat, which turns out to be of French origin. The captain offers the family the chance to go to France, where they’ll be able to speak their mind. When the Simpsons reach France, however, they begin to miss America. They decide to return as part of a group that’s always welcome in the United States: the immigrant without identification.