One day, a medium built stammerer, Jun (Wang Bao Qiang) confesses to five murders at a police station, but fails to illustrate the details, and after a long oral examination the police believe Jun to be mentally unstable as his mentioned murders prove not to exist. Soon after, a cold-blooded murderer unveils a series of mysterious murders in the district where Detective Han (Lau Ching Wan) is stationed. Each victim was executed in different but equally brutal ways. Han knows that he is dealing with a serial killer. Instinct tells him Jun in the suspect after reviewing his recent statements. His team searches Jun's apartment, but apart from a pile of old fairy tale books, no evidence is found there. One night, Han gets inspired when he overhears his wife reading a bedtime story to their daughter mentioning the way to inflict punishment upon villains in the story. Han immediately examines the books found in Jun's apartment and discovers mysterious symbols scribbled on the pages. The punishments described in two of the fairy tales match two of the murders and the evidence shows that three more murders will occur.