About the title
Han Ji-woo is in his final year at an elite school with a special program, usually attended by children of wealthy parents. Although the boy himself is from a poor family and got in thanks to his excellent grades, the school's math program is difficult for him. One day, because of a foolish stunt, Ji-woo is expelled from the dormitory for a month, and, not wanting to upset his mother, he asks to stay in the small room of an elderly school guard — a defector from North Korea whom the students nicknamed "the Communist Officer." When Ji-woo discovers that the man is quite good at solving the most difficult math problems, he persuades the Communist Officer to become his tutor.