The men and boys in Springfield become obsessed with Ultimate Punch Kick and Choke Championships, a violent sport where fighters inflict severe pain on each other. When Marge and her friends stage a protest against the sport, the show's promoter embraces the controversy and challenges Marge to a match, promising to shut down the competition if she wins. She begins to train with rhythmic gymnastics, but her family step in and get her professional martial arts help to give her a real chance at winning.
Marge and her friends are out doing "crazy bowling" and wonder why there are no men in the alley. Marge discovers that all the men, are spending their time viewing the Mixed Martial Arts Ultimate Punch, Kick and Choke Championship. When Marge catches Bart engaged in ultimate fighting in the school yard, she convinces her friends to form a protest group. The women picket the ultimate fighting stadium, but this fails to attract attention. Marge enters the arena to denounce ultimate fighting, and the promoter, Chett Englebrick, offers Marge a compromise. He challenges Marge to a match, and if she wins he will shut down ultimate fighting in Springfield. Marge accepts the challenge, believing it to be for the betterment of the community. Her family is horrified, and Homer, Bart and Lisa try to convince Marge to call off the match. Marge, however, believes the fight is the only way to stop the violence.
Marge then decides to train on her own, practicing rhythmic gymnastics and writing peace words with the ribbon in her backyard, something that apparently doesn't help. Afraid Marge may get hurt or worse, Homer and Carl procure training for Marge in boxing from Drederick Tatum, jujitsu from Akira, Greco-Roman wrestling from Mr. Burns (who wrestled for Yale under the nickname "The New Haven Nuisance"), as well as "bullying" from Kearney, Jimbo, and Dolph (to which they have a punching bag that contains a tied up Martin Prince and Principal Skinner). On the day of the match, most of the town is convinced Chett will win, and he knocks Marge out with one punch. Homer leaps to her rescue, but becomes stuck in the stadium chairs. Bart jumps in the ring to continue the fight. When Marge sees Chet hurting Bart, she bursts into a violent fighting rage and easily defeats him. She briefly relents when Chet forfeits the match and suggests that she give a bow. However, Chet had actually feigned surrendering and attempted to sneak attack Marge. Marge ended up sensing his fowl play, and performs a roundhouse kick to his face, defeating him for good. Marge tries to make a speech about how to end violence, noting that she discovered her own dark side through the course of the fight. In spite of her heartfelt speech, the audience has left to witness a drunken brawl in the parking lot. Homer and Marge leave the stadium with the intention to make love, with Bart challenging Lisa to settle their sibling feud. While they're running toward each other Lisa jumps in the air and the scene is paused for part of the credits, and played again with Lisa knocking Bart unconscious with one punch.