West Virginia, late 1980s: The rebellious Christy (Sydney Sweeney) defies all the small-town conventions of provincial America and refuses to be silenced. Much to the dismay of her conservative mother (Merritt Wever), she also demonstrates her formidable talent in the boxing ring. With unbridled energy, clenched fists and iron discipline, the young woman quickly causes a stir in this male-dominated world. When the experienced trainer and manager Jim Martin (Ben Foster) takes her under his wing, she rises to become the ‘knockout queen’, soon filling large arenas. The two also become a couple in their private lives and get married. But behind the scenes, their relationship turns into a real nightmare. Jim, suspicious and power-hungry, controls her every move and finances his extravagant lifestyle with her prize money. Whilst Christy triumphs as a champion in the ring, away from the spotlight she struggles desperately for self-determination and, ultimately, even for her very survival. To free herself from this spiral of violence and manipulation, she must face the toughest fight of her life…