There are four people who want to become an actor. Their names are Hun, Eun, Jun, and Kyung. After watching the play [QUARTET], they decide to participate in an acting workshop. They are trained by Mirae, the renowned actor of the [QUARTET].
Through the workshop sessions, Mirae is able to look into the inner lives of the four youths. This is because their acting becomes a mirror that reflects their inner selves. For a character creation class, Mirae gives them the diary of a mysterious individual, 'Hyeon'. While exploring Hyeon, the youths get to see deep inside of their minds. The aspiring actors must now face their fears for the final class - scene creation.