Benjamin O'Connell (John Saxon) travels with his son John (Christian LeBlanc) and John' new wife, Katharine (Lisa Waltz), to an empty motel in the mountains where Benjamin and his own wife spent their honeymoon 20 years before. That night, John gets up in the dark, goes into a nearby room, and disappears. Benjamin confesses to Katharine that he cheated on his wife on his wedding night with a beautiful woman in "the dark room," and agreed to give her a child in exchange for his own freedom. Over the years, Benjamin ran into the woman hundreds of times, and met her "nightmare child" many times as well. Benjamin eventually realized that the door to "the dark room" only appears in the dark. He's learned to avoid the nightmare woman by always turning on lights. Now John's been trapped by the woman in "the dark room," but Benjamin refuses to save his son. Instead, Katharine must find a way to do so.