Gyeongseong, a city of dazzling night and splendid desire. The door of the Gyeongseong Detective Agency, located at 45 Iljeong-mok, Myeongchi-jeong, is open. An orphan with no one to rely on, Sohwa, a 16-year-old girl with nothing but courage, is caught in a secret trap. "No, I don't know anything, I swear!" Jung Haekyung, a young man who runs a detective agency by himself. A chance encounter with a girl triggers memories of a past he'd rather forget, and Haekyung sets out to save Sohwa, who has been falsely accused. "If I tell you my name, will you search all over Gyeongseong to find me?"