Dahye and Dawoon are siblings that live together with their parents. Their relationship is a bit rocky since Dawoon has always been their parents' favorite and Dahye holds some resentment towards him. Dawoon, who is a high school dropout, is always in his room playing games. Dahye starts noticing that he's acting weird, and after finding a disturbing story in her brother's computer, she starts fearing him and what he might be capable of doing. So she enlists the help of her aunt and best friend to try and find out what is wrong with Dawoon.

(Source: Lezhin Entertainment)