Haru Kato, a detective working for the Modern Crime Prevention Task Force in the Metropolitan Police Department, has been ordered to work on security at the Classic Car Festival being held in Ginza. At the event, he runs into his former colleagues from the First Investigation Division, who were called in because of a bomb threat. As the time until the bomb is set to explode quickly approaches, he suggests that they should cancel the festival but no one listens to him. In this tense situation, Daisuke Kambe, who claims to be the newly appointed inspector, arrives on the scene.

When Cho-san was a member of the First Investigation Division 19 years ago, he and Takei were assigned to investigate the murder of Daisuke’s mother, Sayuri. At the time, Cho-san entered the Kambe residence to investigate, and Shigemaru, the head of the Kambe family, surfaced as a suspect in the case. However, the investigative task force folded due to pressure from the top brass of the police, and Cho-san was demoted. Now back to the present, after the mysterious death of Imura, the woman who Daisuke brought into the police station, Kato and Cho-san’s suspicions deepen, so they decide to enter the Kambe residence.