All seems well for Eric Bowen (Sam Rockwell), wife Amy (Rosemarie DeWitt) and their three children as they move into their new house in the suburbs of Illinois. Soon, youngest daughter Maddy (Kennedi Clements) begins talking to an imaginary friend, or so the family thinks.

It's not long before sinister spirits wreak havoc in the home, holding Maddy captive and forcing the parents to consult a team of parapsychologists who engage the supernatural entities in a battle for the girl's freedom.