Genre Mix - elementary (primary) school / middle school / high (secondary) school / university (college) / students / teachers / classroom / schoolmates / etc.
Hong Seol, a student from a poor family, meets the rich Yoo Jung, who is her senior at university. They both develop a rather inconvenient relationship after knowing each other.
An old man is found dead, and his housekeeper is charged with the murder. Her defense attorney is surprised to learn the only witness to the crime is a teenage girl with autism.
The film tells the parallel love stories of a mother and daughter. The story of the mother is told partially in flashback (narrative)s.
Nineteen-year-old Li Myung-hoon (T.O.P (entertainer)) never imagined he would become a killer. Born to a privileged life in North Korea, his dream was to become a pianist. But when his father, a North Korean spy, dies disgraced, Myung-hoon and his younger sister Hye-in (Kim Yoo-jung) are sent to a "guilt-by-association" Prisons in North Korea. Their father's superior, high-ranking military official Colonel Moon (Jo Sung-ha) proposes a deal to Myung-hoon: if he goes down to the South as a "technician" (an assassin) and finishes what his father had failed to accomplish, he and his sister will be released from the prison camp. Myung-hoon accepts the deal and undergoes two years of intense training.