In Hong Kong, Wu Zai-Jan is arrested for lingering in the hall of the Police Department with a weird white make-up on his face and brought for interrogation with Inspector Han and his team. The suspect is mentally disabled and tells that he has murdered a man named Cheng Fai. He also calls the detectives “wolves”. The detectives go to Cheng Fai’s apartment to investigate and they 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 is expecting to be promoted and has a troubled marriage, with his autistic son that he does not love and his estranged wife that does not accept his attitude towards their son. On the next morning, Inspector Han and his team have to 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 they made a mistake releasing Wu Zai-Jan and they decide to cover their steps in the previous day solving the case. They discover that Wu Zai-Jan is a psychotic intern of a mental hospital that has just escaped from the facility and is also very connected to an intern that draws in her cell. When other victims are found dead in murders that recall fairy tales, Han and his team fight against time to avoid the fairy tale serial-killer from committing other murders.