In Hong Kong, Wu Zai-Jan is arrested for lingering in the hall of the Police Department with weird white make-up on his face and taken to Inspector Han and his team for interrogation. The suspect is mentally-disabled and says that he murdered a man named Cheng Fai; he also calls the detectives "wolves." The detectives go to Cheng Fai's apartment to investigate, and find that the supposed victim is alive. They return to the precinct and discharge Wu Zai-Jan since he is mentally-disabled, making them waste their time. Inspector Han expects to be promoted and has a troubled marriage; he doesn't love his autistic son, and his estranged wife doesn't accept his attitude toward their son. The next morning, Inspector Han and his team must investigate a murder case and they find that the victim is Cheng Fai, who was found dead in a park with seven stones in his stomach. Han and his team realize that releasing Wu Zai-Jan was a mistake, and they decide to cover their steps of the previous day solving the case. They discover that Wu Zai-Jan is a psychotic mental-hospital intern who has escaped from the the facility and is very connected to an intern who draws in her cell. When other victims are found dead in murders that recall fairy tales, Han and his team fight against time to prevent the fairy-tale serial-killer from committing other murders.