Robert Thorn, an American diplomat working in Italy, hurries to the hospital, learning that his newborn child has died. A local priest invites Robert to adopt a baby who was born at one time with his deceased son and remained an orphan. Robert agrees to this option, but his wife hides the truth, so as not to injure her. Little Damien grows to the delight of his parents. After Robert is appointed ambassador in England, the family moves to London. But after the boy turns five, strange things begin to happen. Teacher Damien commits suicide just during his birthday. And the new nanny is very strange. Thorn begins to pursue a priest who is trying to reveal to him a terrible secret about his son.