The premise of The Omen comes from the end times prophecies of Christianity. The story, set in Fulham, England, tells of the childhood of Damien Thorn, who was switched at birth with the supposedly stillborn child of a wealthy American diplomat with only the husband's knowledge, in order to keep it from affecting his wife. Damien's family is unaware that he is actually the offspring of Satan and destined to become the Antichrist. His father, Robert Thorn (named Jeremy Thorn in the original book), eventually begins to realize his son's true nature with the help of a photographer named Keith Jennings (David Warner), after numerous people connected to Damien die in tragic accidents.

After Damien's first nanny hangs herself at Damien's fifth birthday party, a new nanny, Mrs.Baylock, arrives to tend to him. A priest who knows about Damien begins stalking Robert, and is eventually the one to first point out that Damien is the Antichrist, and that he intends to kill everyone in his way. The priest later dies in a bizarre accident (he is impaled by a church spire hit by lightning), and Katherine, Damien's mother, suffers a fall after being knocked over a railing by Damien.

Robert and Keith seek out the hospital in which Damien was born to find his true mother. They find that the hospital burned in a horrible "accident," along with several people and all of the records. They then learn where one of the survivors, the head priest at the hospital, can be located, and are led there to find he is in grave health. After telling them where to find the mother, he dies.

The mother turns out to have been buried at an ancient and abandoned Etruscan graveyard. They then find her grave, and next to it, Robert's true son's grave. They take off the cover of the grave to find the mother was a jackal confirming the realization that Damien is not human. Keith beckons with Rodger to leave but he wants to uncover the other grave, hoping it contains a similar corpse and to gain hope that his real son could be alive somewhere. But to his horror, the grave holds a human child, and the skull of this child has a wound from a knife in its side - it was murdered at birth. Then they are attacked by a pack of Rottweiler dogs and barely escape the cemetery.

During this turn of events Katherine is thrown out of the hospital window by Mrs. Baylock, and dies. Robert is devastated when he finds out, and later he and Keith journey to Israel to find a man named Bugenhagen, an archaeologist who knows how to stop the Antichrist. Robert learns that he has to stab Damien with the seven daggers of Megiddo to prevent Damien from killing again. Sickened by the fact that the archeologist asked him to kill a small child, he throws the daggers away. Keith runs to retrieve them, but is decapitated gruesomely by a pane of glass atop a runaway truck. Robert returns to London with the daggers, intending to kill Damien.

Returning to his mansion, Robert finds Mrs. Baylock's guard dog (also a Rottweiler) awaiting him. He manages to lock it in the cellar and then goes upstairs to check whether Damien has the "666" birthmark (as explained by Bugenhagen). Seeing it on Damien's scalp after cutting away some hair, Robert has no doubt about Damien's true identity.

Mrs. Baylock attacks him and after fighting her off, Robert attempts dragging Damien down the stairs, only to be confronted by the nanny once again. Robert wrestles with her violently until he manages to acquire a knife, with which he stabs her. She dies and Robert leaves the house heading toward a church to kill Damien at the altar.

When he arrives at the church, he lays Damien on the altar. He reaches for the daggers and pulls the first one out. But just as he is about to stab Damien, the police arrive and order him to stop. When Robert does not comply and tries to stab Damien, he is shot dead by the police.

The movie ends with Robert's and Katherine's double funeral, where they are given an honorable burial, and are blessed by a Catholic priest. The last scene is of Damien holding the hand of the President. The camera focuses on Damien, and he gives a sinister smile. The credits begin to play.

Curse
A documentary entitled "The Curse of 'The Omen'" was shown on British television in 2005. The production of The Omen was plagued with a series of incidents which some members of the crew attributed to the operation of a curse. They wondered if these events were due to supernatural

forces trying to prevent the filming of the movie. Instances include the following:
Scriptwriter David Seltzer's plane was struck by lightning.
Star Gregory Peck, in a separate incident, had his plane struck by lightning.
Richard Donner's hotel was bombed by the Provisional IRA.
Gregory Peck canceled his reservation on a flight. The plane he had originally chartered crashed, killing all on board (a group of Japanese businessmen).
A warden at the safari park used in the "crazy baboon" scene was attacked and killed by a lion the day after the crew left.
Rottweilers hired for the film attacked their trainers.
On the first day of shooting, the principal members of the crew got in a head-on car crash.
This documentary later appeared on the 2-disc 30th anniversary DVD release of The Omen, and in the Pentology DVD set.