; Young-mi is an orphan but manages to live cheerfully, thanks in part to a secret benefactor. Young-mi wants to meet this mystery man someday, but she never manages to glimpse more than his long shadow. From this shadow, however, she comes up with a nickname for her unknown friend, Daddy Long Legs. After graduating from university, she gets a job writing for a morning program at a radio station. One day Young-mi finds an unsent email, with the subject line ; The Letter I Could Not Send, a sad tale of unrequited love. Touched by the tragic letter, Young-mi vows to help the woman who wrote it, just as the mysterious Daddy Long Legs once helped her.