When young Regan begins to play with a ouija board and talk about her friend Captain Howdy, her single actress mother Chris believes her daughter is playing ‘imaginary friends’ games. Or perhaps that Regan misses her father, Howard, an is inventing an imaginary Dad. But she soon finds out there’s something much more sinister and terrifying going on, as her daughter starts making strange predictions, speaking in tongues, levitating – until the entity that’s moved into her daughter’s body identifies itself as the Devil….