The legendary Roberto Duran and his equally legendary trainer Ray Arcel change each other's lives.

Follows the life of Roberto Duran, who made his professional debut in 1968 as a 16-year-old and retired in 2002 at age 50. In June 1980, he defeated Sugar Ray Leonard to capture the WBC welterweight title but shocked the boxing world by returning to his corner in the November rematch, saying 'no mas' (no more).—Anonymous

Growing up in Panama, Durán is home-schooled by Chaflan, who teaches young Roberto some vital life lessons. Later, Duran joins a boxing club with Nestor "Plomo" Quiñones as his coach. As he reaches 20, an American legendary boxing trainer Ray Arcel, who nearly lost his life after being attacked by an unknown assailant in 1953 in New York City and is now living with his wife Stephanie, notices Roberto's raw talent and punching power and takes the young fighter under his wing, becoming his coach. Not long after, Durán then meets a student, Felicidad, with whom he later has five children..