Roy 'Tin Cup' McAvoy, portrayed by Kevin Costner, is a once-promising golfer who now manages a rundown driving range in the small town of Salome, Texas, alongside his sidekick and caddy, Cheech Marin. Struggling with debt, Roy finds himself in a precarious situation where he must sign over ownership of his driving range to Madam Doreen, played by Linda Hart, to settle financial obligations.
Once a contender for professional success, Roy's career took a nosedive when he attempted a risky shot during the PGA Tour Qualifying Tournament, ultimately missing qualification by a mere stroke. Complicating matters further, his new golf pupil, Dr. Molly Griswold, a charming psychiatrist played by Rene Russo, is dating his former college rival, the slick and sarcastic PGA superstar Don Johnson.
As Roy grapples with his unfinished dreams, he shares his unique perspective on golf with Molly, insisting that the sport is akin to poetry—a feeling rather than a formula. Despite Molly's eagerness to absorb Roy's lessons, he dismisses her extravagant spending on golf gear as unnecessary and urges her to truly feel the game. Nonetheless, Molly’s affection for Roy deepens as she endeavors to understand the sport for the sake of her relationship with David Simms.
When David offers Roy a chance to caddy at a high-stakes charity tournament, promising a meager payout, Roy reluctantly accepts, desperate for cash. During the tournament, Roy impulsively challenges David to a risky shot that ultimately backfires, leading to his dismissal and leaving him unpaid.
In dire straits, with debts piling up and having pawned his golf clubs, Roy's determination to impress Molly intensifies. Motivated to win her back, he devises a plan to qualify for the U.S. Open, hoping to demonstrate his worth. Meanwhile, a crucial conversation with Molly regarding romantic risks amplifies their tension, especially as she begins to see the darker side of David.
The qualifiers present Roy with challenges that often see him making reckless choices, much to the frustration of Cheech Marin. Despite destroying his clubs in a fit of frustration, Roy manages to qualify with only a 7-iron in hand, a testament to his raw talent. He invites Molly to witness his triumph, but she declines, further complicating their relationship.
On the first day of the Open, nerves set in, and Roy struggles significantly, failing to play his best. However, as the tournament progresses, Molly recognizes the reality of David's character and opts to break ties with him, culminating in a passionate moment with Roy. After making a daring wager, Roy showcases his skills with an impossible shot, earning the respect of others.
Each round brings new trials, with Roy facing David. Tied for the lead on the final day, Roy must decide whether to take a risky shot. After missing the green multiple times, he perseveres and finally claims victory with a momentous effort, turning an unfortunate score of 12 into a legendary moment in golf history, marked by cheers from the crowd.
Ultimately, although he doesn’t win the U.S. Open, Roy’s journey redefines his life’s purpose. Together, he and Molly look toward a future filled with possibilities, learning that even in setbacks, love—and the game itself—can provide redemption. Back in Texas, they celebrate as Molly reveals Roy's automatic qualification for the next year's tournament due to his outstanding performance.
