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.

Ghang-gheng, the ancient winner-take-all competition in which the deadliest fighters from around the world employ the most spectacular feats of martial arts skills ever displayed in order to win the prized Golden Dragon. But fighting prowess alone will not be enough for Chris to triumph over such daunting foes.