1999, a teenager fell to his death in a dilapidated apartment in Qingxichuan. Then, black plastic bags containing body fragments were found everywhere in Seoul. Cao, a criminal policeman who is being examined for violating the law, was appointed as the investigation captain of the case.

The murderer seems interested in collecting all the parts of the body, dividing each body into six equal parts accurately and putting it with different bodies. When the police found the third body, they found the mysterious woman Xie (Shen Yinhe) according to the clue, because all three victims were her boyfriends. However, Xie at this time unconsciously lost his memory because of his father's sexual violence when he was young. The murderer killed the suspects locked by the police one by one and staged a series of unexpected murder notices. What Xie has to do is to piece together fragmentary memories and find out the murderer who knows himself better than she does.