The track of the old Springfield Monorail (from "Marge vs. the Monorail") is converted into a "sky park". At the official opening, Mayor Quimby turns on the electricity which causes the monorail car to activate and destroy the boardwalk, running down Sebastian Cobb in the process before finally derailing and crashing into a memorial statue of Leonard Nimoy.
At a town hall meeting about the disaster, Mayor Quimby shrugs off Marge's suggestions with sexist remarks after which she is encouraged by her family to run against him for Mayor of Springfield. After an initial slump in the opinion polls, a promise at the candidates' debate to extinguish the tire fire pushes her support above Quimby's, ultimately winning her the election.
However, when the bulldozers arrive at the tire fire, Marge feels sympathy for the landmark's souvenir stand operator who has chained himself to the gates in protest, and calls them off where she is accused of breaking her promise. When Marge and her support team return to the tire fire offering to buy the souvenir stand, she accidentally insults the still-chained owner learning that he was a Vietnam War veteran whose best friend died stepping on a land mine. This further damages her support.
In an attempt to win back voters, Marge holds a live broadcast from the Simpson kitchen which is watched and rated live by her support team (consisting of Lindsay Neagle, Professor Frink, and Julio from Three Gays of the Condo) and a focus group. During this, she chastises Homer's embarrassing antics, filling the room with laughter and causing her approval rating to skyrocket. As a result, she is encouraged to continue to publicly make fun of Homer, who gets a sandwich named after him, and his own balloon in the Thanksgiving Day Parade that "farts" confetti.
When she sees how Homer has been turned into a laughingstock, she visits Quimby at his home to ask if it is possible to balance being a good leader and having a family life. He tells her that it is not, but that the first night out of office, he truly noticed how attracted he is to his wife Martha. She thanks Marge as well for "giving her husband back".
At the christening of a manhole cover, Marge breaks from the script Lindsay gives her and professes her love for Homer. The crowd walks away muttering in disappointment.
Eight years later in the final scene, Marge and Homer walk through a hall dedicated to her political career. Marge suggests skipping one exhibit that they come near, but Homer points out they have to pass through it to get to the building's cafeteria. They then walk through the exhibit that revealed that she was impeached and Quimby was reinstated as the Mayor of Springfield.