Two boys find a beautiful world of magic and wonder when they find a magic marble in an old lighthouse. There they meet Mari and can escape from the growing hardships of their home lives

Kim Nam-woo struggles through life as people around him constantly leave him; his best friend, Jun-ho, is going to study in Seoul and in some ways his widowed mother is "leaving" him too by paying more attention to her new boyfriend. To escape, he goes to a dream world, where he meets a girl named Mari. The story follows Nam-woo in discovering himself and maturing.