Kim Shin (Gong Yoo) was a decorated military general from the Goryeo Dynasty. However, he was framed as a traitor and killed by his master, the young King. Years after his death, he is cursed to stay immortal forever. That meant that he had to endure the pain of seeing his loved ones die as punishment for the soldiers he killed to protect his country. As penance, he becomes an immortal goblin who is tasked to protect certain people from the life of misery. For many years he has tried to break the curse, but for it to come to fruition he has to find a bride. In his quest he meets a grim reaper (Lee Dong-wook) and a high school senior (Kim Go-eun) with a tragic past.