American diplomat Robert (Gregory Peck) adopts Damien when his wife, Katherine (Lee Remick), delivers a stillborn child. After Damien’s first nanny hangs herself, a Catholic priest warns Robert that Damien will kill Katherine’s unborn child. Shortly thereafter, the priest is killed and Katherine miscarries when Damien pushes her off a balcony. As more people around Damien die, Robert investigates his background and suspects his adopted son may be the Antichrist.