Krusty feels pressure from the network to change his show, so he decides to retire for the fifth and final time. Meanwhile, in prison Sideshow Bob becomes outraged when he finds out that Krusty has erased his past by taping over all his old episodes. He gets released from prison and begins plotting his revenge. First he gets an assistant janitor job at Springfield Elementary and then he begins turning Bart into a Krusty killing machine. During the Krusty's final bow, he expresses his regret for what he did to Sideshow Bob just a Bart is about to kill him…