After his girlfriend died in a car crash, sorrowful psychologist Chung Tai Yin spends five years investigating the truth of the incident. His girlfriend once conducted a psychological assessment for a schoolyard murderer. Her report indicated that he lacked a motive or violent tenancies. During the course of his investigation, Chung Tai Yin meets Tung Yat, a genius with Asperger syndrome, and his sister Tung Yuet, whom he is mutually dependent with.