It's only 11 hours into new years and Homers in trouble with the law already. To recuperate government funds, a series of new laws have been passed that make almost everything a heavily fined crime, including telling it like it is and even adding up the total of his fines. On Moe's advice Homer goes to city hall to bribe an official out of his debt, but his impatience leads him to leave a bag clearly marked 'bribe' in the window while he's away. In court, Homer gets furious with Bart for no apparent reason and after getting restrained by the police he is fined $10,000 (which went to Bart as compensation) and then sentenced to 30 years. He is given one option to reduce his sentence. He must wear a camera and mic in a disguise, and infiltrate the Springfield Mafia, and bring down the Don, (possibly underboss, as in one episode, an extremely stereotypical elderly Italian appears to be Don) Fat Tony. In a parody of the award winning movie Donnie Brasco, with elements from The Godfather, and The Untouchables, Homer becomes very close to Fat Tony.
Fat Tony openly gives him his complete trust, meanwhile Homer is transmitting to the FBI. Homer is torn between the law and his newfound friendship. Homer is there for Fat Tony, whether it is putting oregano on his spaghetti and meatballs, or visiting his late wife's grave who was "whacked by natural causes". Near the end of the episode, following the line of Donnie Brasco, there is a big bust. Homer tells Tony to get out of the area, but because he is so confused, Fat Tony hesitates. The FBI comes in. In a tragic display of emotion Fat Tony tells Homer that he was his friend and he trusted him. He then suffers a heart attack, which proves fatal. Homer, given freedom for his work with the FBI is very depressed. Fat Tony was his friend. Homer visits Tony's grave, throwing his disguise on his grave in a poetic apology. He is hit with a shovel from behind and gets knocked out.
Homer awakes to Fat Tony's voice. "Fat Tony?" he says. He then realizes that Tony's near identical cousin "Fit Tony" is standing before him. The major difference between the two is Fit Tony wears a classic mobster tracksuit, and is in excellent condition. Fit Tony is going to whack Homer, but decides not to because Homer's remorse shows him that his cousin lives on inside of Homer. Fit Tony goes on to take over the Springfield Mafia for his dead cousin. When the pressure gets to him, Fit Tony, who now dresses like Fat Tony, eats, gaining weight. He is called Fit-Fat Tony, but gains more weight and is just called Fat Tony. He looks, acts and sounds like Fat Tony, The Simpsons way of making it like it never happened.