In 1984, a struggling ice cream truck driver named Michael Larson stumbles into an audition for the game show Press Your Luck when a contestant fails to show up on time. During his brief encounter with contestant coordinator Chuck and executive producer Bill Carruthers, Larson shares his story but is soon asked to leave when the original contestant arrives. Nonetheless, Carruthers sees potential in Larson's underdog spirit and promptly books him for the taping the next day.
When the show begins, Larson finds himself competing against Ed, a minister who is the returning champion, and Janie, a dental assistant. Initially, he struggles to provide correct answers to the trivia questions posed by host Peter Tomarken. Despite his rough start, Larson manages to earn some spins on the gameboard, but the excitement turns sour when he gets hit by a Whammy, bringing his score down to zero. As the next round begins, the tension rises; Larson quickly surpasses $16,000 by landing on squares that award both money and additional spins.
As Larson's winnings continue to soar, Carruthers and his team grow suspicious, believing he might be cheating. Chuck embarks on an investigation by breaking into Larson's ice cream truck, where he discovers a trove of driver's licenses, license plates, and videotapes. Upon reviewing the tapes, which initially appear like home movies, Chuck realizes they are recordings of previous Press Your Luck episodes. This revelation allows Chuck to discern how Larson has memorized the five patterns of the seemingly random gameboard—his eyes track the light with precision, and his quick celebrations suggest he already knows the outcomes.
In their desperation to stop Larson, Carruthers and his colleagues resort to intrusive tactics to distract him. Despite their efforts, they come to a decision: they can leverage Larson's unexpected success to boost the show's popularity, allowing him to continue winning. With his total winnings exceeding $109,000 and only one spin remaining, Larson is blindsided when his estranged wife Patricia is brought on a phone call by Chuck. Patricia confronts him about signing divorce papers and ends the call, triggering an emotional breakdown. He locks himself in a dressing room, overwhelmed. Ed, feeling compassion for Larson, attempts to console him until Carruthers arrives. Carruthers acknowledges Larson's memorization of the patterns but insists that he is on the brink of becoming a beloved star.
Reassured, Larson returns to the set, greeted by an audience chanting his name. Choosing to pass his remaining spin to Janie, he defies Carruthers' expectations, earning a standing ovation. Unfortunately, Ed's luck runs out when he hits a Whammy and loses all his winnings. Janie takes a few spins before ultimately passing the final spin back to Larson. Strained and unable to see the patterns clearly, Larson closes his eyes, hitting the button to stop the board.
Weeks later, Patricia watches Larson’s triumphant victory broadcast and learns that he has ultimately won cash and prizes totaling $110,237 by surviving his final spin on a prize.
In a mid-credits scene, viewers are treated to a clip from the real Press Your Luck, featuring Tomarken interviewing Larson after his memorable win.
