Bart and Lisa start a lemonade stand, but it is quickly closed due to them not having a vending permit. They get in line at the licensing bureau, only to find that the long line is standing still due to the clerk doing a crossword puzzle. Impatient, Lisa completes the puzzle herself, only to find herself addicted to the puzzles. Eventually, she becomes so obsessed with them that Superintendent Chalmers hands her a pamphlet for the Crossword City Tournament. Meanwhile, at Moe's, Edna Krabappel offers to buy a beer for anyone who breaks up with Principal Skinner for her. Homer ends their relationship, and decides to take a second job in which he helps break up romantic relationships. Grady, one of his old roommates, calls Homer and asks him to break up Grady's and his boyfriend's relationship because he found a new and "better" man in Duffman. Homer successfully manages to break up the couple. After making a good deal of money, he dreams that he is pestered by the "ghosts" of the jilted lovers and thus quits the trade.
At the crossword tournament, Homer bets his money from his breakup business on Lisa and wins big. However, upon hearing Lisa saying that she is wary of the final round, he bets on the other finalist, Gil Gunderson. Gil plays Lisa for her sympathy and cons her into losing the round, which in turn lets Homer win his final bet. Upon realizing that Homer has come into some money by betting against her in the tournament, Lisa gets angry at him and refuses to acknowledge herself as Homer's daughter, even going so far as to take Marge's maiden name and start calling herself "Lisa Bouvier". Feeling guilty, Homer commissions Merl Reagle and Will Shortz to create a special puzzle for the New York Times, with his apology to Lisa hidden in the clues and solution. The two of them make up, and Lisa is happy to call herself a Simpson again.