Robert Thorn is a senior American diplomat whose wife, Katherine, endures a difficult delivery where their newborn child has died. Thorn knows the news will devastate Katherine, who had suffered two previous miscarriages. The hospital priest presents Thorn with another child born that night, whose mother died in childbirth. The priest compels Thorn to take the infant boy as his own; Katherine will never know the truth, and their son, which they name Damien, will be raised as their flesh and blood.

As the child turns five, unsettling events begin to occur: Damien’s nanny hangs herself at the youngster’s birthday party; a strange priest brings dire warnings to Thorn; a children’s trip to the zoo results in a panicked frenzy; Damien becomes hysterical during a drive to church; and blurred movements in a series of photographs portend shocking deaths. Enter Mrs. Baylock, Damien’s new nanny, who seems to have a preordained devotion to the child. Then tragedy strikes closer to home. But only later does Thorn comprehend the truth: Damien is no ordinary child; he is the long-prophesized Anti-Christ. Now, Thorn must make the ultimate sacrifice to prevent the unspeakable terror that awaits the world.