According to legend, the "Thirteen Needles of Ghost Gate", a secret needle of ancient medicine that has been passed down for thousands of years, can save people from the ghost gate and control people with puppets. Everyone wants to get it, but it has long been hidden in the rivers and lakes, and there is no trace to be found. When the world gradually forgot the "Thirteen Needles of Ghost Gate", a weird and unpredictable serial murder case involved the "Thirteen Needles of Ghost Gate" and the Ghost Gate Secret School behind it, and the case became more and more confusing. At the same time, Song Jingzhi, who was expelled from the Ghost Gate for murdering his mentor, inexplicably became the murderer of the serial murder case while investigating the serial murder case. Faced with all kinds of hard evidence, Song Jingzhi and the murderer behind the scenes started a just battle of life and death and redemption. At the critical moment, a disfigured old woman admitted all the charges. The mantis stalks the cicada, and the oriole is behind. It is true and false. Who is the real murderer?