Plot summary

Thorton Melon is a successful and wealthy businessman who owns a nationwide chain of clothing stores for overweight people. Melon himself came from humble beginnings where his father pushed him to succeed in school, however Melon himself, despite his sharp business skills, never attended college. At a meeting of his top staff, he accepts a few new investment ventures and suggests modifying a few more when his son, Jason, calls him. Jason is a student at a prestigious school, Grand Lakes University. His father asks him how he's doing with his studies, if he's enjoying being in a fraternity and if he's doing well as part of the diving team. Jason tells him all is fine but is actually lying to his father; he isn't in a frat and he's only the towel boy for the diving team.Melon's snooty, mean and spendthrift 2nd wife, Vanessa, holds a dinner party for her rich friends at their luxurious house. Thorton mentions that nearly all the people who attend are only there for free food and drink and want to schmooze her for donations. While he raids the fridge for a beer, he catches Vanessa in a tryst with another man, Giorgio. Thorton has known about the affair for some time and when Vanessa demands a divorce, he presents her with papers and shows her several Polaroids of her having sex with Giorgio.After the party, while he practices diving in his pool, Thorton talks to his personal aide and bodyguard, Lou, about how he's let Vanessa weaken his relationship with Jason. He decides he's going to make a surprise visit to Grand Lakes to see his son. When they arrive, Thorton goes to the wrong Greek house - it's a sorority house - and finds out that Jason isn't in a frat or on the diving team. Jason tells him that he's unhappy at the university because he hasn't made very many friends and the frats & diving team don't want him as a member. Thorton tells him that he needs to stay in college so he can be successful in life. He also tells Jason that he'll join him for a semester at the university, enrolling as a freshman.Thorton has no record of his academic achievement to qualify as a student so he persuades the school's academic dean, Dean Martin, by donating money to construct a new building that will house the Thorton Melon School of Business. The school's dean of the business department, Philip Barbay, is appalled that Thorton is able to bribe his way into Grand Lakes. Thorton counters by saying that he has real world business experience that trumps Barbay's academic credentials.Thorton and Jason register for classes and both take Barbay's business course. In the first class, Thorton counters nearly every point Barbay makes about his lesson plan for the semester where they will learn about theory by building a fictional company that will make and sell a product. Later, Thorton and Jason attend a literature class taught by Diane Turner whom Thorton embarrassingly falls for immediately. Though she's seeing Barbay, she seems to enjoy Thorton's freewheeling personality and dates him as well. When Thorton forgets that he's supposed to meet Jason for a study session, Jason instead meets with a young woman who he's smitten with, Valerie, and they bond, despite Valerie's attachment to a snobby student, Chas. Meanwhile, Thorton, while partying at a local bar, comes to the aid of Jason's roommate, Derek, a politically radical troublemaker who'd earlier disrupted a pep rally for the football team. The team's captain threatens to beat Derek when Thorton has Lou intervene, prompting a huge brawl. Thorton later comments that the football team isn't nearly as tough as his high school team was.Thorton also connects with the school's diving coach; the man knew Thorton when he was an entertainment diver on a pier in Atlantic City. The coach tells him that Jason tried out for the team but didn't do well. Thorton has Jason execute a difficult dive for the coach on the spot. Thorton soon finds that he likes the fun aspects of college; hanging out in bars, throwing parties, schmoozing with female coeds, but he doesn't like the academic work involved. He brings in his senior staff and hires people from scientific corporations to do his classwork for him. Jason is angered when his father presents him with an astronomy paper that Jason wants to do himself. Jason becomes further disillusioned with his father when, after he makes the diving team, that his father might have persuaded the coach to let him join.One night during a wild party thrown by Thorton in the dorm room he had luxuriously renovated, Thorton is caught in the hot tub by Diane with several young women. His relationship with her is further hurt when she reads the paper he'd turned in on Kurt Vonnegut, saying that he couldn't possibly have written it himself and that the person who wrote it for him didn't know anything about Vonnegut. (Thorton had called in Vonnegut himself (who appears in a cameo) for assistance.)Barbay soon goes to Dean Martin with charges leveled against Thorton of academic fraud. Thorton lies and insists the work he did was his own but Barbay trumps his claim by suggesting that Thorton's final exams be given to him in oral format so he can't cheat. Thorton begins to pack, wanting to leave. Jason convinces him to stay and that he and his roommate, Derek, and Lou will all help him cram for his finals.When Thorton's big day arrives, he's exhausted. Barbay starts the proceedings, giving Thorton a grueling single question composed of 27 sections. Thorton persists and answers all the parts correctly. When he wants to give up, Diane asks him to recite Dylan Thomas' "Do not go gentle into that good night". Thorton gets a boost and finishes his exams.The Grand Lakes diving team has a match the same day. Jason does very well, earning high points while Thorton watches and waits for his exam results. When the team begins to fall behind their rivals, the diving coach calls Thorton poolside to execute his famous Triple Lindy dive from his Atlantic City days. Thorton is reluctant but Lou talks him into it. Thorton executes the dive, involving bouncing on several diving boards on 3 different levels of the platform and the team wins the match. Diane finds him after, telling him he earned all D's in his classes and one A from her.Thorton is allowed to give a humorous address to the graduating class. He tells them to stay in college and become successful, drawing laughter from the crowd.