The movie begins with Max having a dream where he performs on stage as a rock star to impress Roxanne, but wakes up to find it was just a dream. He is also worried about his dad's plans for their summer vacation, which involves going on a fishing trip to Lake Destiny, which Max finds extremely boring.
Max's friend, PJ, helps him come up with a plan to impress Roxanne by faking a phone call from a famous rock star inviting Roxanne to a concert. However, the principal catches Max in the act and threatens to call his dad, causing him to panic.
Goofy, who is worried about Max's behavior, decides to take him on the fishing trip to reconnect with him and strengthen their bond. Max is disappointed but reluctantly agrees to go, secretly planning to hijack the trip and take Goofy to Los Angeles to attend the Powerline concert and impress Roxanne.
During their journey, Max and Goofy encounter several mishaps, including being chased by Bigfoot and accidentally driving off a waterfall. They also meet Pete and his son, who are also on a fishing trip, and end up joining forces to go white-water rafting.
As they get closer to Lake Destiny, Max's lies catch up with him and Goofy finds out about his real plans. This leads to an argument between them and Max runs away, leaving Goofy to search for him. Max eventually realizes that he was wrong to lie to his dad and goes back to apologize, but runs into trouble with the principal who thinks he is trying to run away.
In the end, Goofy and Max reconcile and make it to the Powerline concert, where Max performs on stage and impresses Roxanne. Goofy is proud of his son and, with their relationship strengthened, they finally make it to Lake Destiny to enjoy their fishing trip together.