Homer attempts to build Marge a spice rack. While he is doing so, Maggie sneaks up behind Homer and hits him on the head with a mallet. Marge is initially clueless as to what would motivate Maggie to do such a deed, but then notices that, when she sees episode of The Itchy & Scratchy Show, a cartoon which is known for its violence, she mimics its content and tries to stab Homer with a pencil. Marge immediately blames The Itchy & Scratchy Show for Maggie's actions and bans Bart and Lisa from watching the show. Despite the ban, they still manage to watch Itchy & Scratchy at their friends houses. Marge writes a letter to the producers of the show asking them to tone down their violence and in response, Roger Meyers, Jr.the CEO of Itchy & Scratchy International writes a letter to Marge, telling her one person can not make a difference and calls her a "screwball". In response, Marge decides to "show what one screwball can do".
The next day, she quickly forms "Springfieldians for Nonviolence, Understanding, and Helping" (SNUH) and forces the family to picket outside the Itchy & Scratchy Studios. Many concerned parents and neighbors rally to her side as they picket against Roger Meyers and the rest of the creators of Itchy and Scratchy. Marge's protest gains momentum and soon more people join the group and even start to picket The Krusty the Clown Show, on which Itchy & Scratchy is shown. She appears on Kent Brockman's show, Smartline where she confronts Roger Meyers over the violence. Meyers refused to listen to her, citing this is what the children to see on Itchy and Scratchy. Marge refuses to give up and suggests that concerned parents send letters to him. Many angry letters are sent to the Studio and Roger Meyers concedes defeat, and agrees to eliminate violence in Itchy & Scratchy. Eventually, a new short in which Itchy & Scratchy sit on a porch drinking lemonade airs, but Bart, Lisa, and other kids across Springfield reject the cleaned-up show. A lengthy montage follows, in which the children of Springfield go outside and engage in various wholesome activities and that night Bart and Lisa brag about their various outdoor activities while Marge listens happily.
Meanwhile, Michelangelo's David goes on a coast-to-coast tour of the U.S. and Springfield is one of its scheduled destinations. The members of SNUH try to urge Marge to protest the sculpture, insisting that it is offensive and unsuitable. However, she refuses and reveals that she believes that the sculpture is a masterpiece. The rest of the SNUH members were dismayed at her response and goes ahead of the protest against Michelangelo's David. While appearing on Smartline, Marge admits that it's wrong to censor one form of art but not another, and sadly concludes that while one person can make a difference, at the end of the day they probably shouldn't. Itchy & Scratchy immediately returns to its old form and Springfield's children abandon their wholesome activities and return to spending every day indoors watching the violent Itchy & Scratchy cartoons. Homer and Marge go to see David and Marge expresses her disappointment that the kids are watching cartoons rather than seeing the sculpture. She cheers up when Homer tells her that the school will be forcing them to go.