In the summer of 1964 two arson cases occur in succession in Tokyo. The Tokyo Olympics are soon to begin the city. The first arson case took place at the residence of Shuuichiro Suga (Ittoku Kishibe). Shuuichiro Suga heads the security staff for the Tokyo Olympics. The second arson case took place at the police academy. There has been little mentioned about the fire cases due to a gag order.
Detective Masao Ochiai (Yutaka Takenouchi) works in the investigation section 1 for the Tokyo Metropolitan Police Department. He learns about the arson cases from his colleague Detective Takashi Iwamura (Takumi Saito]). Takashi Iwamura became aware of the arson cases from rumors.
Several days after the police academy fire, detectives from the Tokyo Metropolitan Police Department gather secretly. Minoru Tamari (Ikki Sawamura), who is the section chief of investigation section 1, and Seiji Tanaka (Ren Osugi), who is the deputy section chief, announce that 2 days prior to the fire at Shuuichiro Suga's residence, the superintendent general received a threatening letter. In addition, a threatening letter was received prior to the police academy fire. With the Tokyo Olympics coming up, the detectives launch a secret investigation into the arson cases.
Detective Masao Ochiai hears that right before the fire at Shuuichiro Suga's home, a man and a woman were spotted in a red sports care in front of his house. From that information, Detective Masao Ochiai is able to determine that the red sports car is owned by Shuuichiro Suga's second son Tadashi Suga (Mokomichi Hayami). Detective Masao Ochiai tries to further investigate Tadashi Suga, but his investigation is suspended by Section Chief Minoru Tamari.
Masao Ochiai and the other detectives continue to work diligently. They also discover that the company Kitano Gunpowder lost some dynamite that was for construction. Detective Masao Ochiai hears that Kunio Shimazaki (Kenichi Matsuyama) works at Kitano Gunpowder. Kunio Shimazaki is a poor student at Tokyo University. Detective Masao Ochiai begins to have suspicions about Kunio Shimazaki. While investigating Kunio Shimazaki, Detective Masao Ochiai learns that his own younger sister Yumi Ochiai (Meisa Kuroki) is dating Kunio Shimazaki.