Eunja lives a wealthy life as the daughter of a top lawyer in Korea. She would sneak out of the house disguise as a boy to compete in composing competition. At the final competition a composer for BAP offers her to compose their song and she takes it knowing that her dad won't allow her to. So she lies to him about going to visit her friend for 3 weeks. For 3 weeks she will get a one shot at living her dream as a composer, but  will she make it in 3 weeks without being discovered that she’s not a boy from BAP?