Fourth instalment of the Bulgarian action drama series 'Boyka'. When Boyka (Scott Adkins) defeats an opponent in the ring who consequently dies of his injuries, he rethinks his career and finds a way to put it right. When he finds out that the man's widow, Alma (Teodora Duhovnikova), is now about to be taken in by gangsters and treated as a slave as her late husband owed them money, Boyka steps in and swears to save her from a life of ownership. The gang doesn't take kindly to this, however, and sets a series of fights against extremely strong and demanding challengers. Can the established fighter prove himself and endure the punishing tasks ahead of him?