Set in the late 19th century, the story follows a young and ambitious San Francisco bank clerk, James J. Corbett, who is drawn to the world of boxing. Coming from a humble background, James enters the sport with determination and tenacity, bringing a sense of style and finesse that contrasts sharply with the brutish nature of boxing at the time. Instead of relying solely on brute force, he employs a strategic approach marked by agility and innovation. Through perseverance, he gains attention and rapidly ascends the ranks, managing to capture the interest of both fans and boxing promoters alike. However, his growing fame isn't without its challenges, as he faces resistance from more traditional fighters and skeptics who dismiss his refined techniques.

As James rises through the boxing world, his charisma and distinctive fighting style captivate audiences nationwide, leading him to earn the moniker "Gentleman." His success also brings him into conflict with established traditions, drawing both admiration and envy from his peers. Alongside his career, James navigates tumultuous relationships, particularly with his family and with a spirited woman who is both impressed by and skeptical of his ambitions. Eventually, his path leads him to a pivotal match against the reigning world champion. This bout represents not just a test of physical prowess, but also an opportunity to redefine what it means to be a champion in an evolving sport. With the eyes of the nation upon him, James must prove that his unorthodox methods can triumph in the face of tough opponents and staunch criticism.