At this point, we have enough Sideshow Bob episodes to give him his own season.
Overview (Spoilers Below)
The Simpsons are coming back from a vacation, and Bart goes missing after falling in a secret manhole in the forest. The town tries to search for him to no avail, leaving Bart to explore the confines of the manhole. Turns out, Bart has stumbled upon a secret nuclear missile silo and is trapped there after the ladder leading outbreaks in his hands. To aid in their search, the Springfield PD makes use of prisoners to cover more ground, and of course, one of the prisoners they use is none other than Sideshow Bob.
Marge is grief-stricken, believing Bart to be gone forever. Thankfully, Milhouse finds him, but finds that by not telling the Simpson family where he is, his long-time crush Lisa will spend time with for “comfort.” Springfield calls the search of, much to Sideshow Bob’s dismay, who begins to lose his mind at the prospect of not being able to kill Bart himself. In his mania, Sideshow Bob escapes and finds Milhouse, who he forces to lead him to Bart’s location. Meanwhile, Bart manages to contact Marge by creating a makeshift telephone, but it breaks too quickly for him to tell her where he is, prompting Marge to take matters into her own hands.
Bob and Milhouse find Bart at the missile solo. In a dastardly plot, Bob ties Bart and Milhouse to the missile stored there with the intent to launch them, but he is stopped when he realizes he needs a second person to turn the nuclear launch key. During this, The Simpson family searches for Bart by themselves, taking Grandpa along because why not. Bob is just about to launch the missile by using his circus talents to stretch across the launch console but has a crisis of conscience wondering if he could have been a good person. He calls his prison therapist to ask if he should kill the boys but ends up having a change of heart. (Not the first time this has happened) He declares that he doesn’t want to kill Bart anymore, and goes back to the Springfield Penitentiary, happy now that he’s resolved his murderous feelings. Flash forward to “Many years later” and we see Sideshow Bob as an old man in a lighthouse, lamenting his many years trying to kill Bart while harassing a hapless mailboy. End of episode.
Like many episodes of The Simpsons this season, this episode is overwhelmingly average. Usually, Sideshow Bob can breathe some much-needed life into an episode with his theatrics and flamboyant villainy, but it just feels like a tired shtick here, and the episode doesn’t seem to take anything about him seriously anymore. I remember waaaaay back in the early seasons when Bob was somewhat of a threat, and you knew you’d be in for an interesting episode if he showed his mug. But this time, he just kind of shows up, in an episode that otherwise doesn’t really go anywhere interesting.