Nick Davis, played by Viggo Mortensen, is a former Marine who went to prison for a crime he did not commit. While in prison, he learned how to fight and survive, skills that will come in handy in his new job. After his release, Nick is struggling to find a job and make ends meet. That's when he meets Shuji, played by Ryo Ishibashi, who offers him a job at the Yakuza-owned warehouse.
Nick is at first hesitant to join the Yakuza, but he needs the money and he feels a sense of loyalty to Shuji for saving his life. Shuji becomes a mentor to Nick and introduces him to his daughter, Yuko (played by Mako Ishino). Nick and Yuko develop a close bond, and Nick starts to feel like a part of the Yakuza family.
However, Nick is actually an undercover FBI agent who has been assigned to infiltrate the Yakuza and gather information about their illegal activities. Nick struggles with his loyalties, torn between his duty to the FBI and his growing connection to the Yakuza.
Things come to a head when Dino Campanela, the leader of the Italian Mafia, attacks the Yakuza warehouse, seeking to take over their territory. Nick fights alongside the Yakuza to protect their interests, putting himself at risk. In the end, Nick must make a choice between his loyalty to the FBI and his loyalty to the Yakuza family that has become his own.