A notorious murderer Oba escapes from jail. Hayasaki, the Oba's right hand, tries to get the money by manipulating the horse racing to send Oba to Hong Kong. But Oba has a plan to revenge the police officer who arrested him and to rob a bank again.
When Nick Davis leaves prison after one year in solitairy, he is hired to operate a forklift in a warehouse in the harbor owned by the Japanese Yakuza patriarch Isshin Tendo. The place is assaulted by the Italian Mafia lead by Dino Campanela and Nick rescues and saves the life of Shuji Sawamoto, who is the representative of Yakuza interests in America. Shuji hires Nick to work for Yakuza and becomes his godfather in the family after his oath to join Yakuza. However, Nick is a lonely FBI undercover agent assigned to penetrate the criminal organization. When the FBI discovers that Campanela is organizing a massive attack to destroy the Yakuza, Nick's boss Littman calls off the operation to leave the dirty work to the Italian Mafia. But the connection of Nick with Shuji and his goddaughter Yuko forces him to help his Japanese family.
When George Tanner does business with high-ranking Yakuza Tono, Tono kidnaps his daughter, and George summons his old friend, private eye Harry Kilmer, to Japan to investigate.
After yakuza boss Kurata dissolves his own criminal empire, a rival kingpin offers a position to Kurata's top operative, Tetsuya "Phoenix Tetsu" Hondo. When the fiercely loyal Tetsu declines, Otsuka taps unstoppable Tatsuzo the "Viper", a ruthless gun-for-hire, to assassinate him. As the Viper trails his target through the countryside, the agile Phoenix Tetsu grows concerned that one of his former associates has betrayed him.