It's the end of another school year at Springfield Elementary School. While Bart and Milhouse discuss their plans for the summer, Lisa is taking care of the distribution of yearbooks. However, even with her academic track record and accolades in the yearbook (she edited the whole thing after Mr. Estes died), she becomes very disappointed when nobody wants to sign her yearbook. Later that day, Flanders makes a deal with Homer to watch over his beach house in Little Pwagmattasquarmsettport while he serves jury duty. The Simpson family head out to the beach house, taking Milhouse along with them.
Seeing this as a chance for a new beginning, Lisa abandons her old, nerdy image, and tries to develop a new persona. She gets a cool new look at the beach, and finds some skateboarding friends: Erin, Dean, Rick and Ben. Trying her best to fit in, she humiliates Bart by telling her new friends that he is a nerd. Bart becomes furiously jealous of the attention Lisa is getting, and attempts to ruin her friendships by showing them Lisa's accolades in her yearbook. Saddened at this event, Lisa runs off.
The next day, the family attends a carnival, where Bart and Lisa continue to fight over the previous night's events. Finally having had enough of her brother's torment, Lisa dejectedly walks back to the beach house. Once she arrives, she discovers her friends have decorated the family car with seashells. When Lisa asks why they would do such a thing for her, they let her know that her yearbook reputation doesn't matter. To them, she's still a great person. Homer walks out and sees the new decorations on his car, and exclaims "Sweet merciful crap! My car!" out of shock and horror at the new decorations.
As the family leaves the next day in their car, with various seabirds also attacking the car due to the presence of shells, Bart returns Lisa's yearbook. He reveals to her that before they left he showed it to her new friends, who all signed little messages inside. Lisa smiles and thanks Bart for the kind gesture, as the Simpsons head home.