The movie starts off with the popular cartoon series in the Simpsons, Itchy and Scratchy. Homer (Dan Castellaneta) complains about a movie based on a cartoon. Green Day wants to talk about the environment, but dies. At their funeral, Grampa has a vision, but only Marge (Julie Kavner) takes him seriously. Lisa (Yeardley Smith) talks to the city about pollution. The mayor orders everyone to stop polluting. Homer dares Bart (Nancy Cartwright) to skate naked. Bart is caught by Chief Wiggum (Hank Azaria). Homer arrives, and they go into Krusty Burger. Krusty (Dan Castellaneta) is about to kill a pig, when Homer adopts him. Homer dumps the pig's waste in the lake. The lake gets polluted, and the town gets trapped in a big dome. The town discovers Homer caused it, and goes after him. The Simpsons escape and moves to Alaska, where Marge discovers that the government is trying to destroy Springfield. Marge and the kids go to save it, while Homer stays. Homer then has a vision, and goes to save Springfield. The bomb is lowered through a hole, and the citizens try to escape through it. Homer arrives, and takes the bomb with Bart. They ride a motorcycle around the dome, and throw the bomb through the hole. The bomb explodes, causing the dome to shatter, and restoring Springfield to the way it was.