According to the movie’s original screenwriter, A. Roy Moore, he based the story off of the urban legend of “ the babysitter and the man upstairs .” This is definitely a story you’ve come across before, as it’s been adapted throughout dozens of different movies — an unidentified caller phones the house in order to scare the occupants inside. In this original legend, while babysitting, the sitter receives a phone call telling her to “check on the children.” Once she does so, she either discovers that the children have been murdered, or she’s lured upstairs to be killed herself.