Genre Mix - elementary (primary) school / middle school / high (secondary) school / university (college) / students / teachers / classroom / schoolmates / etc.
Hong Seol (Oh Yeon-seo) is an ordinary university student. She is busy working part-time jobs to pay for her tuition fee and living expenses. Yoo Jung (Park Hae-jin) is her senior at the same university. He seems perfect. He comes from a wealthy family, he has a kind attitude to others and he is handsome, but Hong Seol does not feel comfortable with Yoo Jung. Suddenly, Yoo Jung comes and talks to her. He wants to go out on a date and they begin an awkward relationship.
An old man suffering from depression is found dead, and his housekeeper, Mi-ran, is charged with the murder. Mi-ran's defense attorney, Soon-ho, is surprised to learn the only witness to the crime is Ji-woo, a teenage girl with Asperger’s. Will Ji-woo be able to take the stand and provide a valid statement?
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.