British ex-Muay Thai champion turned instructor Marcus and his wife Ammara, who are running a training camp in Bangkok. While mourning the loss of their child, Marcus discovers that Ammara’s younger brother Chet, a promising Muay Thai boxer, owes money to a local crime boss — forcing him to participate in a series of brutal underground fights orchestrated by charismatic Nigerian gangster Tiga. As Marcus tries to help Chet get out of trouble, he is coerced by Tiga into replacing Chet in the illegal arena, plunging him and his family into a dark world of visceral violence with much more at stake than he’d ever imagined.