While watching The Krusty the Clown Show, Homer asks what happened to Sideshow Bob, Krusty's former sidekick. Bart and Lisa remind their father of Bob's attempts to frame Krusty, kill Selma, rig an election and kill Bart. Meanwhile, at Springfield Minimum Security Prison, Sideshow Bob is disturbed when he hears the other inmates laughing at the inane antics of Krusty's television show. He believes that television is a fountain of "mindless drivel" and wants to rid the world of it. Bob hatches a plan and escapes while on work duty at a local Air Force Base, which is being cleaned for an annual air show. He impersonates Air Force colonel Leslie "Hap" Hapablap in order to gain access to a restricted area of the hangar, where he finds a 10-megaton nuclear weapon.
The air show begins, with the Simpson family in attendance, but the signal on the big screen is interrupted by Bob. Bob announces that life would be better without television and so he threatens to detonate the nuclear bomb unless Springfield gives in to his demand to shut down all television broadcasts. Upon hearing the announcement, everyone flees the airfield in panic except for Bart and Lisa, who get separated from their parents during the crowd's mad rush to evacuate. National Guardsmen frantically search the base for Sideshow Bob to no avail. All out of options, Mayor Quimby decides to give in to Bob's ultimatum — despite Krusty the Clown's objections. In accordance with Bob's demands, television transmitters are destroyed and studios hastily plan farewell programs. Bob, who was televising his demands from a stolen Duff Blimp, celebrates the success of his plan.
Krusty, refusing to submit to Bob's demands, takes refuge in a civil defense shed in the desert. He uses the emergency broadcast system to transmit a heavily improvised show. Bob finds out about this and becomes outraged. Bart and Lisa find their way into the cockpit of the Duff Blimp, where Bob, having lost his patience thanks to Krusty, tries to detonate the bomb. However, the bomb turns out to be a dud (there was a label inside the bomb saying "Best Before November 1959") and does not blow up. The police eventually find Bob, thanks to Lisa, who uses the controls inside the blimp to print a message on its electronic ticker outside. When Chief Wiggum tries to arrest Bob, Bob deflates the blimp and kidnaps Bart. Bob steals the original Wright Brothers aircraft, which had been an exhibit at the air show. He then reveals to Bart that he plans to start out a kamikaze attack into the civil defense shed where Krusty is hiding. However, the plane ends up merely bouncing harmlessly off the shack. The authorities quickly arrest Bob and take him into custody while Bart is reunited with his family.