Sinister tells the story of Dr. Alan Keaton (played by Cillian Murphy), a true-crime novelist who moves his family to a remote farmhouse in the countryside. Keaton's latest book, "Sinister," chronicles the infamous deaths of a family at the hands of a serial killer. However, when Keaton stumbles upon a box of disturbing home movies in his attic, he becomes obsessed with uncovering the truth behind the tapes.