At the Mid-County Community Center, a coach quits teaching a ragtag team of aspiring martial artists. Charlie, the community center leader, is on the hunt for a new mentor when Jimmy Lee, a former mixed martial arts champion and Charlie's protégé whose career stalled three years earlier after an accident, arrives. Reluctantly, he agrees to coach the group, consisting of Wyatt, Leticia, Raymond, Ricky, and brothers Alex and Sean, as he works toward a possible MMA comeback.
The kids carry weighty personal struggles: poverty, bullying, a longing for approval, and the pain of parental loss. Jimmy slowly warms to them, recognizing their needs and earning their trust in return. His patient guidance helps them begin to grow, both as a team and as individuals, and the sense of possibility returns to their lives.
When the team heads to their first competition, Jimmy runs into his old childhood rival, Ted Barrett, who coaches the three-time national karate champions, the Beverly Hills Scorpions. Ted weaponizes his fame to influence others, even as his own son Eric objects to his ways. The younger players suffer humiliation, and Jimmy—driven to secure support for the team—tries to find a sponsor. Ted retaliates by smearing Jimmy's name and ensuring he’s blacklist from potential backers. Just when hope seems dim, Big Mama, a friend and food truck owner, steps in with a sponsorship. To seal the deal, Jimmy makes a bold, humiliating move at the next event by appearing in a hot dog costume, a stunt that earns sympathy and attention for the Underdogs, the team’s new nickname.
With renewed energy, the kids accept the name and push forward. Jimmy adds another recruit, Rasheed, a quiet yet volatile fighter whose mother wants him to channel his intensity into self-discipline. As training intensifies, the Underdogs begin to win more often, building confidence and camaraderie. A big tournament looms, and the prospect of facing the Scorpions becomes real.
To help with balance and rhythm, the aunt Valerie Cruz encourages ballet lessons for the team. The fresh approach gives them grace in their movements, though it also introduces a moment of vulnerability as the Scorpions uncover their training and post the footage online, triggering taunts and renewed pressure, especially on Rasheed who battles a speech issue that becomes a point of ridicule.
Jimmy’s bond with Rasheed deepens after a tense confrontation at home, and they discover common ground that strengthens their resolve. Meanwhile, Jimmy earns an opportunity to return to MMA, but he leaves the day before the big showdown to weigh a contract in Las Vegas. The decision weighs on him, and he ultimately realizes MMA may not be the path for him anymore. He returns in time to lead the Underdogs into the climactic confrontation.
The final showdown unfolds with a series of one-on-one matches that ends in a tense tie. The tiebreaker is a group kata, and the Scorpions post a score of 49. The Underdogs, energized by a last-minute, creatively arranged a cappella beat arranged by Rasheed's brother and friends after the music is sabotaged, deliver a flawless performance and earn a perfect 50. The Underdogs win, and the moment is sweeter for the sense of sportsmanship that follows: Eric joins in congratulating the Underdogs, and the two teams declare a new friendship. Ted Barrett’s sponsor cuts ties with him in disgust over his unsportsmanlike conduct, signaling a quiet turning point in the rivalry and a vindication for Jimmy and the Underdogs. The story closes on a note of resilience, teamwork, and the idea that guidance and hard work can transform a group of underdogs into champions.
