Goofy is the single father of a teenage boy named Max Goof in the town of Spoonerville, Ohio, though the two have a tense relationship. On the last day of school before summer vacation, Max and his best friends P.J. and Robert “Bobby” Zimmeruski hijack the auditorium stage in the middle of Principal Mazur’s speech, creating a small concert where Max performs, while costumed as the pop singer Powerline. The performance succeeds in making Max a school celebrity and impressing his love interest, Roxanne; but he, P.J. and Bobby are sent to Mazur’s office. Roxanne speaks with Max and agrees to go with him to a party where Powerline’s concert will be aired live. However, Mazur exaggerates these events to Goofy and forewarns him that Max’s actions may result in him facing capital punishment.
Goofy decides to take Max on a fishing trip to Lake Destiny, Idaho, following a map route he and his father took years ago, and the two go into his station wagon. However, he is oblivious to what Max is planning to do with Roxanne. Max stops by Roxanne’s house to call off their date, but when Roxanne says she will just have to go with someone else, Max instead fabricates a story about his father knowing Powerline; he tells her he will be on stage at the concert.
Despite his son’s objections, Goofy plans his own trip, with initially disastrous results. Max hurts his father’s feelings after his father humiliates him at an opossum-based theme park. While camping, Pete and P.J. join them. Following Pete’s advice to keep Max under control, Goofy takes his son fishing and performs the Perfect Cast fishing technique, luring Bigfoot to their camp. Pete and P.J. flee, leaving Goofy and Max to spend the night with Bigfoot. At night, while Goofy is still asleep, Max alters the map route to Los Angeles, where the concert is taking place.
The next morning, Goofy decides to make Max the navigator of the trip. The two go to several locations that satisfy both of them. They stop by a motel where they meet Pete and P.J. again. When Pete overhears a conversation between Max and P.J., he tells Goofy that Max has tricked him in traveling to Los Angeles. The next day, Goofy and Max come to a junction: One leading to Idaho, the other to California. Max chooses the route to California, making Goofy stop the car and storm off in anger. With the brake loose, the car drives off on its own; Goofy and Max chase after it and end up at a river. Goofy reveals that no matter how old Max gets, he will always be his son and the two reconcile with each other. After learning that Max had promised Roxanne that he would be at the concert, Goofy decides to take him to Los Angeles. The two nearly plummet down a waterfall to their deaths, but Max fortunately saves Goofy, using the Perfect Cast technique.
Goofy and Max get to Los Angeles and they end up onstage and dance with Powerline, watched by Pete, P.J. and Roxanne on separate televisions. Goofy and Max later return to Roxanne’s house in their damaged car. Max tells the truth to Roxanne, though she accepts it and admits she always had feelings for him, ever since he first said, “Ahyuck!”; thus, a relationship starts between them. Goofy’s car suddenly explodes due to the damage it has sustained, ejecting Goofy in the process, but he safely falls through the porch roof of Roxanne’s house, and Max proceeds to introduce him to Roxanne.