Moon Chae Won, 22 year old university student becomes a replacement teacher when her friend, Hyo Joo asked Chae Won to replace her during her vacation due to marital leave. She hopes that during those 3 months as replacement teacher, everything will run smoothly and she can keep her calm. However, Ji Chang Wook, a 17 year old high school student really ticks her nerves when he acting like a rebellious student. what will happen between one teacher, that proclaim herself that she will not give