In the midst of one of their arguments, Bart and Lisa fall into Professor Frink's basement. Frink uses an astrology-based machine to show the kids their future as teenagers.
Eight years in the future (2013), Bart and Lisa are getting ready for their high school graduation and Homer and Marge have separated after Homer blew the family savings on an undersea home. Lisa is graduating two years early and has a scholarship to Yale University, while dating a muscular Milhouse and Bart dates a skateboarder named Jenda. He also shows them a picture of Lisa at age 12 (2009) after she was saved by Milhouse from a fire (which she later learns that he started). After the prom, Jenda wants to have sex with Bart, but Bart has no plans for the future and wants Jenda to marry him and live an aimless life, so she breaks up with him.
Bart unsuccessfully seeks advice from Homer on dating. He then shows Lisa a hologram of the prom, and tells her love can be painful; she agrees, noting she broke up with Milhouse and he had an Incredible Hulk-style meltdown. Lisa suggests that to get Jenda back, he must show her he can provide for her. Bart decides to take Lisa's advice and gets a job at the Kwik-E-Mart. While delivering groceries to an elderly Mr. Burns, he rescues him from a robbery by Snake Jailbird. As a reward, Burns gives Lisa's scholarship to Bart. He accepts it, seeing it as a way to get Jenda back. He then tells Lisa about the scholarship causing present and future Lisa to both get angry at Bart. Bart reconciles with Jenda, and now has a good future. That night, Jenda again wants to have sex with Bart, but then he goes into Professor Frink's basement and sees Lisa's bleak future with Milhouse on Frink's machine. Jenda is furious at Bart (she notes she never had any problems sparking romance with Todd Flanders), and gives him an ultimatum: leave and they are finished. Bart does head out and saves Lisa from accepting Milhouse's dismal proposal, then tells his sister he is giving her scholarship back and will find a woman who loves him for himself. Professor Frink then tells present Bart he will get one at age 83, then die one minute later, and his brain would be buried in a pauper's grave.
Meanwhile, Marge has dumped Krusty and reunites with Homer in the underwater home. During the credits, Bart is shown to find the sequence boring, and instead watches Cletus Spuckler's future as the Vice President of the United States on his way to a funeral for the Sultan of Brunei.