Criminal profiler Jang Tae-su is a well-known figure in South Korea. He pioneered the area of criminal behavior analysis in the nation and was among the first in his field. Within the police structure, he has earned everyone's respect and trust. At home, he is raising his daughter Jang Ha-bin alone as a single parent. He had one son that died from falling off a cliff, despite his daughter's young age he believes she pushed him. He kept Jang mostly confined to her room and questioned her repeatedly about that night. She often cries until her mother saves her, but always glares at her father. The mother eventually dies of suicide, but evidence once again points to foul play. In the course of investigating a murder case some years later, Tae-su discovers that his daughter is in some way involved. His connection with his daughter and his professional ideas are completely upended by the revelation. In order to keep his daughter safe, Tae-su finds it difficult to tell the truth.
