Twelve year old Regan MacNeil begins to adapt an explicit new personality as strange events befall the local area of Georgetown. Her mother becomes torn between science and superstition in a desperate bid to save her daughter, and ultimately turns to her last hope: Father Damien Karras, a troubled priest struggling with his own faith.
When two girls disappear into the woods and return three days later with no memory of what happened to them, the father of one girl seeks out Chris MacNeil, who's been forever altered by what happened to her daughter fifty years ago.