"Bart the Murderer" is the fourth episode of Season 3. It first aired on October 10, 1991. The episode was written by John Swartzwelder and directed by Rich Moore. The episode features references to songs such as "Witchcraft" and "One Fine Day", and the American television series MacGyver.
After having a very lousy day of school, Bart accidentally stumbles into `the Legitimate Businessman's Social Club,' a mobster front. He becomes their bartender, but when he shows up late at work and blames Principal Skinner, Fat Tony then goes to confront Skinner. The next day when Bart comes to school, he discovers that Skinner is missing.
The day begins with Bart preparing for the school day, during which he is supposed to go on a field trip to the chocolate factory. But his day quickly turns sour, as Homer steals his cereal prize, Santa's Little Helper eats his homework, and he misses the school bus and arrives late for school. During recess, he rips his pants, and finally, he realizes he forgot his permission slip for the field trip, and is forced to spend the day at the school with Principal Skinner.
On his way home from school, he wipes out skateboarding in front of a local mafia hangout. They take him in, and after he coincidentally picks a winning horse for mafia don Fat Tony, they tell him to mix drinks for them. Bart reads in a chart how to make a Manhattan, and makes Legs a "supoib" one, so they hire him as their bartender.
Not knowing that his new boss is a mobster, Bart begins to unwittingly help Fat Tony, accepts a gift from him, and even hides a stolen cigarette shipment in his bedroom. But soon, it becomes apparent that Bart has been taken in by criminals, and Marge instructs Homer to go and see what kind of people Bart is working for.
Homer is extremely oblivious, as he approves Bart's job after the mobsters intentionally lose at poker in order to curry Homer's favor.
Carrying over his new persona into the schoolyard, Bart gets a detention for trying to bribe Principal Skinner. As a result, he is late for work, where the Fat Tony has promised his mafioso guests the "finest Manhattans in all of Springfield." Bart arrives later, and is reprimanded by Fat Tony. When Bart explains that his absence was due to Principal Skinner, Fat Tony decides that he and his associates will go to 'meet and greet' him.
Shortly afterwards, Skinner goes missing. Bart suspects Tony may have something to do with it, and begins to have nightmares about Skinner's death. Bart runs to the mob headquarters, where they deny having killed Skinner. During their chat, Chief Wiggum and his officers enter Tony's hangout, arresting everyone in there for Skinner's murder.
A trial begins, and Lionel Hutz acts as Bart's lawyer. On the stand, Bart is upset to find that Fat Tony and his gang name Bart as the head of their organization, pinning any issues regarding Skinner's disappearance (as well as everything else they did) on him. Just when it seems that Bart is going to be found guilty, Skinner bursts into the courtroom, and tells everyone that he was in fact trapped under a pile of newspapers in his garage for a week. The case is dismissed, and Bart quits his job at the Legitimate Businessman's Social Club.