Reverend Lovejoy recommends Sideshow Bob—now a model prisoner who claims he is a reformed man—for a work release program. Bob’s brother, Cecil Terwilliger, hires him to supervise a construction crew building the new Springfield Hydroelectric Dam. When word spreads throughout town that Bob was released from jail, angry Springfield residents gather outside the penitentiary. The most vocal of the protesters is Bart, who fears his old nemesis is faking a transformation for the sole purpose of wrecking havoc upon the city.

The brothers discuss their long-standing rivalry—which stems from a 1986 audition in which Krusty chose Bob to play his sidekick. Incredibly bitter, Cecil believes he was born to play the clown’s second-banana, and now faces spending the rest of his life as a Chief Hydrological Engineer. Meanwhile, Bart begins spying on Bob from afar, hoping to foil whatever diabolical plot his arch enemy has concocted. Bob carries Bart and his sister back to the Simpson home, insisting he cannot be held responsible for his actions if the children continue monitoring him. Despite this, Bart and Lisa gain access to a construction trailer, where they search for incriminating evidence. They discover a briefcase containing a million dollars in cash.

Bart and Lisa dash out the trailer door and run inside the dam’s interior, where they are cornered in a turbine room. Lisa accuses Bob of embezzling the money during the dam’s construction. But Bob insists he is a reformed man. With that, Bob bangs on a dam wall, causing pieces of concrete to break lose from the ceiling. Cecil, carrying a gun and dynamite, steps forward. He explains it was he who embezzled the money. Cecil plots to blow up the dam and frame his brother in the process—all because he lost the audition. He locks the threesome inside the turbine room, taking the dynamite and briefcase with him. The threesome escape and, in an act of heroism, Bart and Bob defy death and manage to thwart Cecil’s scheme, saving Springfield. Bob thanks Bart for saving his life during their encounter with Cecil. But when Chief Wiggum arrives at the scene, he arrests both brothers and sends them to prison.