High school junior Scott Howard (Michael J. Fox), at seventeen, is tired of his mundane existence and yearns for something extraordinary in his life. His father, Harold (James Hampton), operates a local hardware store, while Scott struggles to make an impact on his basketball team, the Beavers, who are languishing at the bottom of the league. With their win-loss record dismal, their coach contemplates forfeiting matches against the top competitors to avoid the embarrassment of defeat. Among his teammates is Chubby (Mark Holton), who is notably overweight.
Scott's heart is set on Pamela Wells (Lorie Griffin), the girl of his dreams, who is currently dating Mick (Mark Arnold), a bully from the rival school team, the Dragons. Best friend Boof (Susan Ursitti) has feelings for Scott, yet he remains oblivious to her affections. As Pamela participates in the school play, Scott contemplates quitting basketball to spend more time with her in hopes of getting noticed.
After yet another loss, Scott starts experiencing alarming physical changes—increased hair growth on his chest, heightened sensitivity to sounds, rapid heartbeat, and an unusual rash. Meanwhile, his friend Stiles (Jerry Levine) is preparing for a party and needs Scott's help to procure a keg of beer. When denied service at a liquor store for lack of ID, Scott surprisingly intimidates the attendant with a newly discovered throaty voice and glowing red eyes, securing the purchase.
At Stiles' party, where fun and games ensue, Boof feigns pulling Scott's name for a closet challenge with wild expectations, but he winds up in quite the unexpected situation that leaves Boof furious. Eventually, Scott secludes himself in the bathroom, while his father pleads for access. When Scott ultimately succumbs to his transformation, he becomes a werewolf—only to discover that Harold had kept the family secret hidden, hoping it would skip a generation.
Terrified that he will turn into an outcast because of this new identity, Scott grapples with the idea of being a werewolf. His father tries to counsel him, showcasing the benefits of his condition, but the initial fear lingers. As Scott navigates these changes, vice principal Rusty Thorne keeps a suspicious eye on him.
In a climactic turn, Scott reveals his werewolf self during a basketball game, captivating the audience. Embracing his supernatural ability, he transforms into a star player, elevating the Beavers from last place to the top and winning Pamela’s attention, much to Boof's dismay. Meanwhile, Stiles exploits Scott's newfound fame, launching a mini-empire of merchandise dubbed "Wolfmania."
Things heat up when Scott earns a significant role opposite Pamela in the school play, leading to an intimate encounter that ultimately ends in disappointment, as she conveys her lack of romantic interest. Faced with numerous moral dilemmas, including conflicts with Thorne and his father's insistence on being the best version of himself, Scott eventually agrees to take Boof to the Spring Dance—yet chooses to show up as The Wolf.
Their dynamic takes a turn for the better as they share a tender kiss, revealing Scott's true self once more. The dance culminates in unexpected chaos when Mick's jealousy flares, leading to a confrontation. This ends with Scott forsaking his werewolf persona for the crucial final basketball game against the Dragons.
In a gripping finish, Scott demonstrates his true prowess without the wolf transformation, leading his team to victory by overcoming a last-minute foul from Mick and sinking critical free throws. After the game concludes, amidst celebrations, he chooses to embrace Boof over Pamela, sealing their connection with a heartfelt kiss, while Pamela storms off in frustration.
