Lights, camera, action!
Frankie Dunn (Eastwood) may be getting on in years, but he's still the best cut man in boxing. He owns Los Angeles's Hit Pit gym, which is looked after by his best friend, former fighter Eddie "Scrap Iron" Dupris (Freeman). Scrap also narrates the film (because everything is better with Morgan Freeman narrating). When Maggie Fitzgerald (Swank), a waitress and would-be fighter, originally from small-town Missouri, asks Frankie to train her, he says he doesn't train girls.
Maggie keeps practicing at the Hit Pit anyway, and when Frankie's best fighter, Big Willie Little, jumps ship for another less cautious manager, Frankie agrees to train Maggie. When he's not working with Maggie, he attends mass everyday, seemingly just to antagonize his priest. He also pens letters to his estranged daughter Katy, which always return unopened.
Maggie trains with Frankie for several months and her skills improve greatly. Still, he's cautious—Scrap would say too cautious—about putting Maggie in an actual fight. When she makes the mistake of asking Frankie about his family, he pawns her off on another manager, Sally. Sally's no good, though, and Maggie and Frankie are quickly reunited.
Maggie knocks every opponent out in the first round. Pretty soon, nobody will fight her because she's so awesome. Frankie bumps her up a weight class, and Maggie gets her nose broken in the victory.
Hey, you win some, you lose some.
After Frankie turns down a series of title fight offers, Scrap secretly sets up an "accidental" meeting between Maggie and Mickey Mack, the manager who nabbed Big Willie. Maggie tells Mickey she'll never leave Frankie. Frankie tells Maggie they're going to England for the British title fight.
Maggie fights all across Europe, and the crowds go crazy for her and the Gaelic nickname, "Mo Cuishle," that Frankie gave her. He refuses to tell her what it means. And we refuse to tell you how it's pronounced.
Back in the States, Maggie buys her mom a house, and her mom is utterly ungrateful. She tells Maggie she's an embarrassment because she's a boxer, but, yes, please, she'll take more of the money that Maggie sends her. On the drive back to L.A., Maggie tells Frankie a story about her dad, who passed away, and the favorite dog he had to put down when it couldn't get around anymore. Then she tells Frankie he's all she has. They stop in the middle of nowhere at Ira's Roadside diner for pie. Maggie's dad used to take her there.
Maggie and Frankie head to Las Vegas where she fights The Bear, a notoriously dirty fighter, for the WBA welterweight title. The Bear lands a cheap shot while Maggie has her back turned between rounds. As she falls to the mat, Maggie hits her head on her corner stool.
She's completely paralyzed.
Frankie never leaves Maggie's side. He calls doctor after doctor, but nobody can fix her spine. He has her moved back to Los Angeles. Maggie's family shows up and tries to get her to sign all of her assets over to them. Maggie tells them to take a hike. Forever.
After losing a leg, Maggie asks Frankie to help her end her life. He says he can't. Maggie tries to take her own life by biting her tongue several times. Bereft, Frankie consults Fr. Horvak, who tells him that if he helps Maggie, he'll be lost forever. Frankie feels like, at this point, keeping Maggie alive is killing her. To keep Maggie from trying to bite her tongue again, the staff sedates Maggie heavily. When Frankie visits, she doesn't even know he's there.
Frankie sneaks into the rehab center to help Maggie die. He tells her that "Mo Cuishle" means "My Darling." She smiles and cries. Then he removes her respirator and gives her a fatal dose of adrenaline. When she's gone, he leaves.
Scrap tells us via voice-over that he never saw Frankie again, but he hopes he found a peaceful place to spend his days. As it turns out, Scrap's been telling this whole story to Frankie's estranged daughter in a letter. The final shot of the film is a peek into the cloudy window of Ira's Roadside Diner, where it appears that Frankie's eating at the counter.