While watching a horror movie show hosted by Boobarella (the show's take on Cassandra Peterson's Elvira character), a commercial plays for the Ribwich (the shows take on McDonald's McRib sandwich), a new Krusty Burger sandwich in which meat from an unknown animal is processed and molded into the shape of ribs. Homer cannot wait for it to come to Springfield. Homer samples the Ribwich, recently arrived at the Krusty Burger in Springfield, and becomes addicted.
The next day at a school assembly, Principal Skinner announces that the school is holding a spelling bee. Lisa is excited when she wins the school spelling bee, for which she is awarded a scale model of the planet Mars (a kickball with the word "Mars" written on it). She continues to the state spelling bee, and wins again, qualifying her for the Spellympics to be held in Calgary.
Marge suggests they celebrate by going to a movie, but Homer says he has "important daddy business" — which turns out to be eating Ribwiches with Lenny and Carl. Unfortunately, when they arrive at Krusty Burger, the limited-time-only Ribwiches are no longer in stock. Homer is shattered, but a "Ribhead" (a fan of the Ribwich) tells him that it is being tested in other markets and shows him a tour schedule. Homer decides to follow a group of Ribheads as they track the release of the Ribwich.
At the Spellympics, hosted by George Plimpton, Lisa wins the semi-finals and secures a spot in the finals. The other two finalists are Sun Moon, a Korean girl, and Alex, a cute little boy with big round glasses and a speech impediment who proves to be extremely popular. Plimpton takes Lisa aside and tells her that if she lets Alex win, she will be given a free scholarship to any Seven Sisters college—and a free George Plimpton hot plate ("it's perfect for soup!"). Lisa is torn between wanting to win the Spellympics and free college.
That night, Lisa dreams of an ancient Greek setting in which the anthropomorphized Seven Sisters try to lure her to their colleges. She wakes up and asks Marge whether they can afford to send her to college. Marge is unsure, but promises to do whatever it takes to get Lisa into college. Despite Marge's reassurances, Lisa is still uneasy since she is aware of how low Homer's salary is and how unlikely Marge's hopes are.
In San Francisco, Krusty informs all the Ribheads that the Ribwich can no longer be made, as the animal from which it is made is now extinct. He tosses the last one into the crowd. Homer catches it, fighting off the others. An Italian Ribhead offers Homer the "lease-a" to his car for the last Ribwich, and Homer remembers Lisa and the Spellympics. He agrees to the trade and takes off in the car.
At the Spellympics finals, Lisa steps up and is asked to spell "intransigence". She is about to start, when Homer shows up and shouts encouragingly at her. Lisa, happy to see her father, tells everyone that she was told to take a dive, but then unintentionally misspells her word. Lisa loses, and since she did not do it on purpose, Plimpton rescinds his offer.
On the way back to Springfield, Homer tries to cheer up Lisa when she admits that she let down everyone in town. However, she finds that in coming second she has become Springfield's most successful native ever (even outachieving the Springfield woman who once dated Charles Grodin). In her honor, the town carved Lisa's face on the side of a mountain.