Lisa finds out how umpopular she is at the end of the school year when no one signs her yearbook. While the family packs for the summer vacation at Flanders's beach house, she prepares to change her life.

Arriving in Little Pwagmattasquarmsettport, Lisa buys clothes befitting a generation X wannabee. Avoiding the pitfalls of her superior vocabulary and intellect, she succeeds in making friends with a group of "cool" beach kids.

Jealous of Lisa's new-found popularity, Bart plots revenge. He shows the beach kids Lisa's yearsbook and points out all the nerdy, unhip things she did at school. Lisa is furious at Bart, thinking that his disclosure has turned her friends away. Arriving home from a carnival, however, she finds them in the act of decorating the Simpsons' car with hundreds of seashells in her honor. They explain that they like Lisa for who she is. To make up with Lisa, Bart has them all sign her yearbook.