In the summer of 1963, in the vibrant borough of Brooklyn, New York, 18-year-old Jeffrey Willis receives an invitation to celebrate the Fourth of July at the exclusive El Flamingo Beach Club situated in Far Rockaway, Long Island. At the club, he reunites with old neighborhood friends, Steve Dawkins and Henry "Hawk" Ganz, who require a third player for their gin rummy game. With his exceptional talent for both math and card games, Jeffrey helps them clinch a win of $89.90. As he revels in the club's luxury, he becomes captivated by the stunning, blonde Carla Samson from California, who is visiting with her affluent relatives, the Brody family.
Following an extravagant buffet and dazzling fireworks display, Jeffrey notices a car trouble in the parking lot. Displaying his skills, he manages to get it running again, which earns him a job offer from the parking lot attendant. The next morning, he eagerly shares with his father, Arthur Willis, a plumber who had other plans for him—namely a position as an office boy at an engineering firm in Brooklyn. Arthur, who dreams of his son embarking on an educational path, discourages Jeffrey’s decision to work for tips, dismissing it as an unworthy endeavor.
At the El Flamingo, Jeffrey witnesses a high-stakes gin rummy match where the "king" of the game, Phil Brody, a foreign car dealership owner, takes on retired Colonel Cal Eastland. Enthralled by Phil's unique card-holding technique, Jeffrey tries to emulate this skill in the privacy of his thoughts. An invitation to dinner at the Brody residence follows, where Phil's wife, Phyllis, disapproves of Jeffrey's presence. Nevertheless, Phil warms to Jeffrey after he praises his card-playing prowess, endeavors to mentor him in the game, and fosters a blossoming connection with Carla during the evening.
Promoted to cabana boy shortly after, Jeffrey revels in his earnings and victories at gin rummy with friends. Phil decides to further introduce him to his world by taking him to Brody Motors, allowing Jeffrey to drive a sleek Italian sports car. He shares his belief that while education is important, sales ability reigns supreme in achieving financial success. Inspired, Jeffrey confides in his family about abandoning his college aspirations for a future in sales, which angers his father, who had high hopes for Jeffrey’s educational journey.
Amidst escalating tensions between father and son, Arthur attempts to bond over dinner, but Jeffrey opts to hit the horse races instead, leading to a series of setbacks that culminate in an arrest following a bar fight. This confrontation shakes the family dynamic; Arthur reluctantly bails Jeffrey out, resulting in a heated argument about finances. After a clash of wills, Jeffrey decides to leave home, challenging his father’s values which leads to an emotionally charged exchange about finding happiness and purpose.
Utilizing his initiative, Jeffrey finds himself ready to embrace his new job at Phil's dealership, albeit starting from the ground up as a stock boy rather than the sales position he covets. A meaningful romantic encounter with Carla unfolds on the beach, marking a significant moment in their relationship before she returns to college.
As Labor Day approaches, a high-stakes gin rummy game unfolds once again, with Phil competing against Colonel Eastland. Observing a man named Big Sid signaling Phil regarding Eastland's cards, Jeffrey seizes the opportunity to step in when Big Sid collapses. This pivotal moment transforms the dynamic of the game and positions Jeffrey in a triumphant spot against Phil, leading him to score significant winnings while unveiling Phil's cheating strategy to his teammates, changing the course of his summer.
Ultimately, Phil acknowledges Jeffrey's exceptional ability while extending a job offer to become a salesman at his new dealership in California. However, Jeffrey declines, standing firm in his integrity by exposing Phil's dishonesty, and chooses to return home to mend the relationship with his father, asserting his determination to take a different path by saying goodbye to his friends at the beach club and moving forward.
