The body of a young lady, who had been fatally stabbed in a back alley of Yokohama's shopping and entertainment district, is discovered. Four detectives from the Fourth Section of Minato-cho Police Precinct's Criminal Affairs Division " Togashi Masayoshi, Iinuma Reiko, Shibata Yasuharu and Yamashita Manabu " quickly rush to the scene. Togashi finds something in the pocket of the dead body and nonchalantly hides it in his own suit. He presumes Reiko and the others will turn a blind eye even though they have noticed it.
Detectives from the prefectural police's First Investigative Division arrive shortly after that. The members of the Fourth Section, who have been deprived of their right to investigate by the First Investigative Division, dejectedly walk away from the scene. However, they secretly begin their own investigation.
Three days later, Satonaka Keiichiro, the Fourth Section's new chief, arrives. Satonaka himself believes he has been demoted to the precinct because of he denounced the unfair appointment of the prefectural police chief's nephew. However, the objective of Maejima Ryuzo, the head of police administration who sent him into Minato-cho Police Precinct, is to let Satonaka keep tabs on Togashi and the Fourth Section. Maejima warns Satonaka that there is a "bad rumor" about the Fourth Section.
Togashi and the others are seen as misusing their high arrest rate and frequently disobeying the orders of the prefectural police. In fact, they are even suspected of all kinds of illegal activities which include extorting confessions under duress, having cosy ties with crime syndicates and accepting bribes. Tokunaga Yasushi, the former section head who was investigating the facts, had lost his footing on the rooftop of a building while pursuing a robber and had fallen to his death... Was Tokunaga's death really an accident?!
Satonaka regards his new subordinates with caution but the four of them are unexpectedly affable and excellent detectives, especially Togashi who is a stimulating and gallant man. They give Satonaka a thorough report on the investigation into the murder which occurred three days ago, and say that they are searching for eyewitnesses in line with the prefectural police's position that it was a "random attack". He feels relieved to see their serious manner. However, several days later, Satonaka discovers that their entire report was nonsense...!