At the age of thirteen, Do-hyun (Baekhyun) moved to Pyongyang, the capital city in north korea to pursue his dreams of becoming a singer , leaving behind his best friend Lee Ji-eun (IU) in Seoul. They kept in touch but because calls were expensive , they eventually stopped communicating. Later on, Ji-yoon's father is offered a job in Pyongyang so her whole family moves there. She enrolls into an academy of arts and meets a boy very much like her childhood friend..