The story takes place in a place called Anlan City. This city is prosperous and stable on the surface, but it hides all kinds of unknown secrets and sins in the dark. Anlan City has jurisdiction over several districts and counties. The story mainly focuses on a relatively ordinary county that has become unstable due to a series of serial murders. Behind the story, there is a mysterious criminal organization. This organization has been involved in many serial murders. Their superb crime techniques and tight organization have brought great difficulties to the police's investigation work. The identities of the members of this organization are mysterious. They may have penetrated into all levels of society, and may even be inextricably linked to certain forces within the police. The existence of this organization is an important suspense in the story, and it is also the key to the shocking secret that the two heroines need to uncover.
