The Black Phone follows a 13-year-old boy named Finney Shaw who is kidnapped by a masked serial killer called The Grabber and locked in a soundproof basement. While trapped, Finney starts receiving phone calls on a disconnected black phone from the killer’s previous victims, who try to help him escape before he becomes the next victim. At the same time, Finney’s younger sister Gwen has psychic dreams that help police search for him, leading to a tense and emotional ending where Finney finally fights back against his captor.