Moments after his son is born in Rome, ambassador Robert Thorn is approached by a priest and told that the baby is dead, but that a replacement can be offered. Thorn accepts the offer, agreeing not to tell his wife. Soon after Thorn is appointed as US ambassador to England. A series of strange deaths begin to surround the child Damien as it grows up. A priest comes to Thorn, telling him the child is the anti-Christ, a son of the Devil. Thorn has him thrown out but shortly after the priest is bizarrely killed. Soon events force Thorn to confront what the priest says as truth and he and a journalist set out on an international quest to find a means of killing Damien.