 Maggie Fitzgerald, a poor thirty-one year old waitress from the very lower classes and with a dysfunctional loser family, decides to make a difference through boxing. She convinces the experienced hardened boxing trainer Frankie Dunn to coach her and be her manager, with the support of his old partner Eddie Scrap-Iron Dupris, who sees her potential as a boxer. Frankie has a problematical relationship with his daughter, and practically adopts Maggie along her career.