After being abducted by a child killer and locked in a soundproof basement, a 13-year-old boy starts receiving calls on a disconnected phone from the killer's previous victims. In 1978, a serial child abductor nicknamed 'The Grabber' prowls the streets of a Denver suburb. Finney, a bullied teenager, and his sister Gwen live with their abusive father. Gwen has psychic dreams and foresees the kidnappings. The police search for Finney is unsuccessful. Finney receives help from the ghost of a previous victim and manages to escape. With Gwen's help, they confront the killer and free themselves.

Set several years after the events of the first film, The Black Phone 2 reunites us with survivors Finney and Gwen as they attempt to move forward. But the past refuses to stay buried. When a new string of disappearances strikes the area, it becomes clear that something—or someone—has returned. And the black phone? It’s ringing again.