Sum is a developer for social connecting app "Somebody." Even though she has difficulty communicating with other people, she is friends with Mok Won and Ki Eun. Her friend Ki Eun works as a detective. A murder takes place and the app "Somebody" is involved in the murder case. Architectural designer Yoon O appears in front of Sum and her friends. Yoon O is an attractive man, but he seems to be hiding something. Meanwhile, Ki Eun investigates the murder case with help of Mok Won. Adapted from the novel “American Psycho” by Brett Easton Ellis.