Cheng Feng, a 37-year-old ordinary librarian and archivist in Qifeng Town, used his inconspicuous identity to build a secret underground labyrinth prison, and successively abducted four young women and imprisoned them for seven years. For a time, rumors about the "man-eating monster" spread wildly on the Internet. The police station dispatched a female special police undercover to rescue the hostages within 24 hours. The female undercover went deep into the prison step by step to engage in a life-and-death game with Cheng Feng, and finally discovered the shocking secret of his split personality. Cheng Feng discovers Chi Jie's identity as a female undercover, and uses a designed game to force a fight between the female undercover and the hostages. Cheng Feng kills one of the female hostages. The female undercover is challenged by humanity's ultimate challenge and finally succeeds in rescuing the other hostages.