Jang Tae Su is a legendary criminal profiler in Korea. He was one of the first in his field and paved the way for criminal behavior analysts in the country. He has gained the absolute respect and trust within the police organization. At home, he is a single parent and raises his daughter by himself. Jang Tae Su works on a murder case and realizes that his daughter is involved in the case. The discovery shakes everything in his professional beliefs and his relationship with his daughter. To protect his daughter, Jang Tae Su struggles to reveal the truth.