Everybody in Springfield (Except the Flanders, Lenny and Carl) have had enough of the Simpsons' shenanigans, and decide to banish them from town. The family settle in a deranged town, where they pick up new skills like Maggie hunting with a crowbar. Lenny and Carl miss the family and decide to pay a visit. Soon, everybody in Springfield decides to rebuild Springfield where the Simpsons live now.
The Simpson family are at home watching Channel 6 News where Kent Brockman announces that there is a disaster and that everyone has to go into their underground bunkers. After saying it was a drill, and then acting like there was an actual disaster again, he tells everyone to go into their shelters for three hours and not to come out. The Simpsons head to their shelter.
After a while, the family is all bored and decides to head out of their shelter to explore Springfield while it is empty. They then go past Springfield Town Hall where they realize that there is a secret meeting going on. They sneak in to find that the town has voted to kick them out of Springfield. After making themselves known to the rest of the town, the townspeople act angry at them. They then reveal that it was a mixture of Homer's recklessness, Bart's vandalism in school and in town, Lisa's environmental pleas and Marge's niceness that got them kicked out. Ned attempts to defend them and tells the citizens to give the Simpsons a break. However, it falls on deaf ears and reveals the Flanders as the only residents who voted against exiling the family. Quimby tells Ned off that his attempt to defend the Simpsons reveals his family own corruption and intentionally ejects the Flanders out of the hall. The Simpsons are then paraded out of Springfield.
After driving for a while, Bart says that he needs to pee. They stop to let him go and are then held up by a guy with a shotgun. After Marge explains their situation to him, he welcomes the family to The Outlands. The family starts new here and begins to enjoy life. Marge is having a hard time settling in. When the family confronts her about it, they learn Marge is homesick for Springfield. She dislikes their new neighbor, Julian Assange, as she sees him rude and unkind unlike the friendly Ned Flanders and her concerns that Maggie is falling in with a rough crowd. To cheer Marge up and despite knowing they're in exile, Homer then decide to sneak her back into Springfield.
Homer and Marge, disguised as Mr. Burns and Waylon Smithers, sneak back in, presumably tricking Clancy Wiggum in the process. They have a romantic night together then head to their old home where they go to bed. In bed, they hear Jimbo, Dolph and Kearney come in and are found out. Before the bullies can tell anyone, the police come to the house along with the rest of the town. Chief Wiggum tells Homer and Marge that he had seen through their disguises and pretended to be fooled in order buy himself time to gather the residents together. He and the other cops are prepared to arrest them, but Marge tells them not to bother doing so because they're leaving. Homer calls the crowd jerks for trying to arrest them just because they wanted to visit Springfield. Upon realizing how much the disillusioned citizens hated the Simpsons(minus the Flanders), Marge is furious and tells them off. She admitted she was homesick to return to Springfield, even if they don't want the family around anymore. Now that she knows the truth, Marge prefers to return to the Outland because her new community accept the Simpsons for who they are and the family is free to love each other without the constant spite and judgment from their former neighbors. Homer and Marge leaves for their new home, leaving the townspeople to start having second thoughts on kicking the Simpsons out.
The Simpsons are settling into life in The Outlands until Lenny, shortly followed by Carl, turn up, saying that after what Homer and Marge said, they wanted a better life too. Lenny admit Springfield wasn't the same after the Simpsons were exiled out of the town and he along with Carl wants a fresh start. Eventually, Moe turns up too, opening Moe's Cavern for them to drink at. After that, Mayor Quimby, and many other Springfield residents show up, wishing to abandon their lives in Springfield and start over in The Outlands. Soon, all of Springfield moves there to start new lives with the Simpsons and they begin rebuilding a new city. Mayor Quimby names it Springfield, which Marge is truly against stating it takes away the charm of being known as The Outlands and has always disliked the corruption form the old Springfield. The man whom the Simpsons befriended decides to pack up and move further away from the people. Eventually, Seymour Skinner is the last person left in Springfield, until Bart rescues him in a wooden helicopter, crashing him into several buildings and landmarks.
At the end of the episode, a title card appears stating:
"Thanks for 500 Shows.
All we ask is that you go out
and get some fresh air
before logging on the Internet
and saying how much this sucked."