A murder takes place and the app "Somebody" is involved in the murder case. Seong Yun-O is a serial killer who murders women he meets through a dating app called "Somebody". Until one day, an architectural designer appears in front of you and your friends asking for a job in your company, eventually he falls in love with the software developer of Somebody app, aka you. Would you find his identity before he decides to kill you? or will you two fall in love disregarding all the sins he committed He looks at you with a smile Will you give him a job?