Bart appears in court to pay for an embarrassing joyride in the police chief's patrol car, but just before he is set free, a second, vindictive The Evil judge named Constance Harm The Evil Lady assumes the case and sentences him to the worst kind of detention imaginable: being tethered to Homer around the clock.
After missing the school bus, Homer takes Milhouse and Bart to school. Homer hears on the radio an announcement for a KBBL's "Prize Possie" radio contest, and whoever gets spotted with the radio station's van and has a "KBBL Party Penguin" hanging from the car antenna wins a prize of $40. Immediately after the announcement, Milhouse spots the van crossing traffic. Homer then abandons Bart and Milhouse on the side of the road and sets out to chase the prize van. The boys start to walk to school by themselves, until they notice Chief Wiggum's squad car. They get inside and mess around in the front seat, but accidentally put the car in neutral after being threatened by the squad's canine in the back seat. After crashing the police car into a tree, Wiggum puts Bart and Milhouse in custody for assuming they used the car for a joyride.
In juvenile court, Milhouse gets his case dismissed for Judge Snyder believes that "boys will be boys". Bart, not worried about any punishment as he believes that Snyder is "the good judge", comes up to face his trial. Snyder is just about to let Bart free when abruptly the judge's vacation starts. The replacement judge, Constance Harm, isn't a pushover, and is just about to sentence him to juvenile detention, but after realizing that Homer was the one who abandoned Bart in the first place, she orders that Bart and Homer be tethered together for the time being.
At first, both of them are unhappy about the punishment, but after the pair attend school, work and Moe's together, the two begin to bond. The bond ends shortly, however, when Bart gets fed up of being tethered after almost having to sit through Homer and Marge having sex. Bart starts a fight with Homer, frustrating Marge, which causes her to cut the tether. Unfortunately, Judge Harm catches her through firewall cameras in the tether rope. Judge Harm decides that both Bart's parents are unfit, so she has Homer and Marge put into wooden stocks and punishes them by making them bend over by the road so people can drive by and spank them (or in Nelson's case, whip them). Later, Homer and Marge use Ned Flanders' table saw and candle to break free. In retaliation, they go to Harm's houseboat to put up a "Big Meanie" banner across her front door. Just when they were about to leave, Harm's pet seal alerts her. Harm runs out, while Homer throws a cinder block at her head. He misses but hits her houseboat, therefore sinking it.
Homer and Marger are brought before The Evil Judge Harm again. She complains that one of her quilts in that boat was made by her grandmother, to which Homer implies if it "cost you nothin'." Homer and Marge are almost sentenced to gruesome punishment. However, Bart interrupts the trial and confesses that he should be the one punished, not his parents. Harm's harsh expressions briefly softens and she admits that she appreciates his honesty. However, Harm reveals she still must lay down the law. She is ready to punish Bart and send him to juvenile hall when Judge Snyder's vacation expires, putting him back on the case. Snyder moves for a motion that "boys will be boys" and dismisses the case. Judge Harm tries to protest against it, claiming Snyder has always been too lenient and she is sent on her way. While going home, Marge makes the family promise that they will never break the law for a whole year. Homer immediately breaks the promise by unintentionally running over Hans Moleman.