Once again, Sideshow Bob is released from Prison, on the condition that he is looked after by his brother, Cecil Terwilliger, an upstanding citizen and head of construction on the Springfield Hydroelectric Dam. Immediately upon Bob's release, Bart suspects that his old nemesis is up to no good, but can't find any proof. Bob tries to get his life together, taking a job on the dam project for Cecil. Their suspicion growing, Bart and Lisa snoop around the construction office and find a briefcase full of money. Just then, Bob catches them, but claims not to know the origin of the cash. It turns out that Cecil is the evil one, hatching his own plan to embezzle money from the dam budget and then destroy the town of Springfield with an explosion. Bart and Lisa overcome their distrust of Sideshow Bob and work with him to stop the destruction. Busted by the Springfield Police Department, Cecil is sent to jail. Bob is sent too, since no one believes that he didn't play a part in his brother's scheme.