Sum (Kang Hae-Lim) is a developer for social connecting app "Somebody." Even though she has difficulty communicating with other people, she is friends with Mok-Won (Kim Yong-Ji) and Ki-Eun (Kim Soo-Yeon). 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 (Kim Young-Kwang) 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.