During the Joseon Dynasty, lowborn Chae-sun challenges the rule that states only men allowed to sing while navigating devotion to her teacher and the demands of the king's father.

Chul-soo is a man with an intellectual disability. One day, Chul-soo finds out that a young girl, Saet-byul, who is in hospital is his daughter. And soon, Saet-byul sneaks out of the hospital and travels by herself to a faraway city for her friend's birthday. As Chul-soo accompanies Saet-byul's journey, friendship develops between the two.