Monroe Hutchens is the heavyweight champion of Sweetwater, a maximum security prison. He was convicted to a life sentence due to a passionate crime. Iceman Chambers is the heavyweight champion, who lost his title due to a rape conviction to ten years in Sweetwater. WHen these two giants collide in the same prison, they fight against each other disputing who is the real champion.

Heavyweight Champ George "Iceman" Chambers is sent to a Russian jail on trumped-up drug charges. In order to win his freedom he must fight against the jailhouse fighting champ Uri Boyka in a battle to the death. This time he is not fighting for a title, he is fighting for his life!

Russian inmate Boyka, now severely hobbled by the knee injury suffered at the end of Undisputed 2. No longer the feared prison fighter he was, he has declined so far that he is now good only for cleaning toilets. But when a new prison fight tournament begins - an international affair, matching the best fighters from prisons around the globe, enticing them with the promise of freedom for the winner - Boyka must reclaim his dignity and fight for his position in the tournament.

In the fourth installment of the fighting franchise, Boyka is shooting for the big leagues when an accidental death in the ring makes him question everything he stands for. When he finds out the wife of the man he accidentally killed is in trouble, Boyka offers to fight in a series of impossible battles to free her from a life of servitude.