Principal Skinner announces a school field trip in a submarine, but warns that only the best-behaved students will be allowed to go due to space limitations. Any student who breaks a rule is barred from going on the trip. Bart behaves well in order to remain eligible, but Skinner crosses him off the list after he tracks mud into the school. After Bart unsuccessfully attempts to curry Skinner's favor and trick Skinner into reinstating him by impersonating President Obama, Homer sees how upset Bart is and decides to help him get revenge on Skinner.
The next morning, Skinner finds his mother's corpse in the kitchen, stabbed to death. Homer and Bart soon discover the corpse despite Skinner's attempt to hide it, and Homer offers to clean up the mess and sends Skinner upstairs. Agnes stands up, uninjured and having taken part in the scheme, and Bart and Homer tell Skinner that the police are coming to arrest him. They provide him with a fake ID and a disguise and put him on a bus to Juarez, only to be shocked when he turns up at their house later that day. Skinner explains that he cannot run away from his crime, but also admits that he is probably glad to have killed Agnes. Marge and Agnes interrupt, having overheard this confession. Agnes is angry that Skinner had wanted her dead along with the fact that he broke his promise to Bart and decides to punish him further by being even meaner to Skinner by not taking the pills that keep her temper in check.
Meanwhile, Lisa learns that Krusty the Clown has gone bankrupt. She suggests that Krusty sell the foreign rights to his show; he does so, demanding a large percentage of the stars' earnings. The foreign shows quickly become more popular than his own, but instead of doing the right thing in allowing the stars to keep more of their money, he offers to do a guest shot on every show. This suggestion angers them so badly that Krusty and his agent are forced to flee on a golf cart. While fleeing, Krusty admitted that he wanted to take the foreign shows' money because he was jealous of their success and he was the only one that was deemed a failure.