As Bart and Lisa walk home from school, they get into a fight. They wrestle each other to the ground, roll down a hill, and plummet through an open basement window. Professor Frink greets them, unfurling a banner that reads, “Welcome Bart and Lisa.” Confused, Lisa asks Frink how he knew they were coming. Frink says he’s mastered the science of astrology, and has invented a machine that can see into the future. Frink turns a dial on the machine, and we see the Simpson home some eight years into the future. Marge tells 18-year-old Bart and 16-year-old Lisa it’s time for their prom photo. A short time later a muscle-bound, teenaged Milhouse shows up at the front door, followed by a fun-looking girl on a skateboard. The girl turns out to be Jenda, Bart’s prom date. The foursome take a limousine to school. There Lisa and Jenda make their way to the girls’ bathroom, where they discuss how Lisa got accepted to Yale University on a Monty Burns scholarship. That night Bart and Jenda make their way to a cliff with a magnificent view of the city. As Bart and Jenda make out, Bart asks Jenda to marry him. Jenda tells Bart she outgrew him. She gives him a kiss on the forehead and walks away.

Teenage Bart tells Homer that Jenda dumped him. Unfortunately Marge dumped Homer for blowing all the family’s money on an underwater house. Homer tells Bart they’ll find some new lady friends. They make their way to Moe’s bar, where Homer tries fixing up Bart with Mrs. Krabappel. When Bart returns home, he learns that Lisa broke up with Milhouse, and that Marge is now dating Krusty the Clown. Bart decides that what he needs most is a new career. He takes a job at Kwik-E-Mart, where Apu sends him out to deliver groceries to Mr. Burns’ mansion. When Bart enters the mansion, he walks in on Jailbird, who is in the process of robbing Mr. Burns. After Bart overpowers Jailbird, a grateful Burns offers him a scholarship to Yale. Bart is tempted to take the offer, especially when Burns says that women love an Ivy-Leaguer. Since Lisa has already won the scholarship and is headed to Yale, Bart is reluctant to break his sister’s heart. The offer is too good to turn down, however, and he accepts it. Later he gives Lisa the news. Lisa screams with rage.

Lisa gives a speech at high-school graduation. She says her dreams were crushed by her backstabbing brother. Jenda tells Bart he did the right thing, and has finally gotten his act together. Later, as Bart and Jenda walk down the street, Bart notices Frink’s rundown house. Bart and Jenda enter the basement, where Bart gets Frink’s astrological prediction machine up and running. This allows Bart to peer into the future, where he sees Lisa, saddled with Milhouse, sobbing and miserable. Bart tells Jenda he must leave. Jenda tells him that if he leaves now, she won’t be part of his future. Bart makes his way to the cliff overlooking the city, where Lisa and Milhouse are about to kiss. Bart throws himself between them. As they walk home, Bart tells Lisa he wants her to have the scholarship. Marge dumps Krusty after realizing Homer is the only man for her.