Ryan Cole (Scott Adkins), a retired underground fighter, has left behind his violent past and now lives a quiet life running a gym for troubled youth. But when his younger brother, Jake, a small-time gambler, gets into trouble with a powerful crime syndicate known as The Blood Circle, Ryan’s world is shattered. The syndicate’s leader, Viktor Dragunov, forces Ryan into a brutal underground tournament in exchange for Jake’s life.

Ryan enters The Blood Circle, a no-holds-barred fighting tournament where the world’s deadliest fighters compete. Each round brings more violence, with Ryan facing mercenaries, assassins, and martial arts masters. Meanwhile, he learns that the tournament is more than just a fight—it’s a front for a sinister organ-trafficking operation, where losing means death.

Ryan forms an uneasy alliance with Mei Ling, a rogue assassin seeking revenge against Dragunov. Together, they plot to bring down the syndicate from within.