Lisa is studying Mayor Quimby's re-election campaign. Listening to a radio show hosted by Birch Barlow, she hears the familiar voice of Sideshow Bob, who is in prison. Bob explains that his sentence is unjust, and Barlow agrees that he should be set free. Mounting support for this cause leads Quimby to release Bob.
However, Sideshow Bob promptly runs for mayor of Springfield, and wins in a landslide victory. He quickly moves to demolish the Simpson home in order to make room for the "Matlock Expressway".
Bart & Lisa don't believe that Bob could have won fairly, so set out to expose him. Acting on a tip off from Smithers, they discover that most of Bob's voters are dead people (and dead animals). Bob is arrested and sent back to prison.