The assassination of Tokyo governor Takayama causes a stir of public outrage in Tokyo, Japan. Upon hearing the news of the incident, the Federal Bureau of Investigation asks the Central Intelligence Agency's Tokyo office to investigate the killing, believing it to be linked to the Yakuza, a dangerous Japanese mafia. Retired CIA agent Travis Hunter and rookie FBI agent Sean Mac are assigned to work on the case and to track down the perpetrators. The Japanese branch of the CIA starts sniffing around under the auspices of the United States Department of Homeland Security. During work, Mac proves to be more of a distraction, not really knowledgeable about procedures or Japanese customs. Hunter was raised in Japan, and has a strong understanding of the Yakuza and their mysterious, eccentric, and sinister ways.