In the midst of serving his prison sentence, Jimmy Dworski (James Belushi), a dedicated fan of the Chicago Cubs and a talented car thief, is on the verge of an extraordinary experience. Just a few days remain until his release when he unexpectedly wins tickets to the World Series. Unfortunately, the warden, Frank Toolman (Héctor Elizondo), denies him early parole, which propels Jimmy to devise a bold plan alongside his fellow inmates. Using the chaos of a prison riot to his advantage, Jimmy manages to escape and heads to the sought-after game.
As he navigates the unfamiliar freedom, Jimmy stumbles upon an uptight advertising executive’s Filofax, left behind by Spencer Barnes (Charles Grodin), who is offering a generous reward for its return. Seizing the moment, Jimmy takes on the persona of the unsuspecting Spencer and embarks on a wildly unconventional adventure. He effortlessly charms his way into the sleek Malibu beach house of Spencer's boss, captivating his daughter with his charisma, while securing a key meeting with Sakamoto (Mako), a formidable figure in the Japanese food industry.
In a twist of fate, Jimmy's unconventional business acumen, demonstrated during a casual tennis match that includes besting Sakamoto and openly critiquing his mediocre products, intrigues the awe-struck executive. Yet, as Jimmy's antics escalate, they inadvertently tarnish Spencer's reputation, leaving the real Barnes to face a downward spiral, stripped of his possessions, car, and stability.
Meanwhile, the genuine Spencer Barnes finds himself spiraling into despair, relying on his former love, Debbie Lipton (Anne De Salvo), who is determined to rekindle their romance. While Jimmy's charade unravels, the two finally meet at a crucial advertising executive gathering, resulting in Spencer's boss losing patience with him due to Jimmy's bizarre tactics.
In a sudden and unexpected gesture, Jimmy invites Spencer to join him at the World Series, where an unforgettable moment occurs: Jimmy makes a stunning catch on a home-run ball hit by Mark Grace in a cameo appearance. As security begins to close in on Jimmy, who is captured on the Jumbotron, he and Spencer ingeniously use the Filofax to escape by sliding down a support wire to safety.
As Spencer's marriage stabilizes, he finds redemption and, with Jimmy's secretive help, manages to sneak him back into prison. Having completed his remaining hours, Jimmy is ultimately freed. In an almost poetic twist of fate, Spencer awaits Jimmy's release, eager to offer him a promising career in advertising and introduce him to a new romantic possibility. The triumph of the Chicago Cubs in the World Series beautifully parallels Jimmy's renewed optimism and the bright future that lies ahead.
