Synopsis：In the Jinling Prison, a mysterious assassin from the martial world breaks in, but the victim is merely a miner from the silver mine. The Six Doors, upon imperial order, immediately dispatches investigators to the Jinling Prison to look into the case. One would expect the elite Six Doors to send their finest detectives, but instead, four young and inexperienced female constables arrive. Though young and female, each possesses unique skills and a chivalrous heart. The four gradually piece together clues and discover the murder is linked to the Jinling silver mine. It seems someone was embezzling funds and silenced the victims when discovered. When their investigation implicates the largest gang, the Jiulong, they confront the mine supervisor Chen Zengzhi, only to find him murdered like the county magistrate Zuo Hengzhi. The four's senior brother Mu Changfeng decides to return to the capital to report, but is ambushed on the way, gravely wounded and left unconscious. Meanwhile, the four realize that Zuo Jing, the son of the magistrate, and his master Xiao Tiannan may be using their martial connections to collude with Chen Zengzhi in embezzling the silver mine and silencing witnesses. Without the protection of their senior brother, the four young women rely on their unique skills, peel away layers of deception, and eventually escape danger to capture Xiao Tiannan, recovering the missing silver mine for the court.