In order to win the ongoing war against their once fellow beings, the ruler of Angels sends his son Taehyung down to earth to capture a special someone who holds the key to everything. Accompanying him on his mission are his two most trustee warriors Baekhyun and Hoseok. Following his father's orders, Taehyung sets off to earth to find a girl named Kim Taeyeon. 

Kim Taeyeon is a human(?) girl who is living her life as an idol. She is a part of a trio group called TaeTiSeo in South Korea. Although Taeyeon lives in a life of luxury and fame, something deep down inside of her tells her that she was never normal. Raised by her single mother, Taeyeon never got the chance to know who her father was but on her 21st birthday, Taeyeon encounters a stranger who claims to know about her father's whereabouts. Desperate to find answers about her father, since she can't get anyting out from her mother, Taeyeon befriends this stranger in order to find out more about her father's mysterious disappearance. It is then that her life turns upside down, something that she wished it never happened.