Damien Thorn (Sam Neill), now 32 years old and head of his late uncle's international conglomerate, is appointed Ambassador to Great Britain, the same position his adoptive father held in the first film. Unlike the previous Omen films, the adult Damien is now entirely aware of his unholy lineage, and his destiny.An alignment of the stars in the Cassiopeia region of the night sky causes the generation of a 'superstar', described in the film as a second Star of Bethlehem. Thorn realizes it is a sign of the Second Coming of Christ and he orders all boys in England born on the morning of March 24, 1982 (the morning when, in the story, the Cassiopeia alignment occurred) to be killed in order to prevent the Christ-child's return to power.A subplot deals with one of Thorn's disciples, Harvey Dean, attempting to hide the fact that his own son was born at the appointed time; Dean not only fails at hiding that fact about his child from Damien, but is killed by his own hypnotized wife - likely in retaliation for refusing to go through with Damien's command to murder his son as a test of loyalty (the last child whom Damien suspects).Thorn has also become romantically involved with journalist Kate Reynolds (Lisa Harrow), a complex relationship which undermines his plans for political dominion for the time being. But Damien is not deterred from his plans and even focuses his attention on her preadolescent son Peter (Barnaby Holm), whom he takes as a disciple, partly by manipulating and exploiting the boy's internal desire to have a father-figure.Meanwhile, Father DeCarlo (Rossano Brazzi) and six other priests armed with the seven daggers of Megiddo - ancient holy weapons which are the only Earthly weapons which can harm the Antichrist - hunt Thorn in the hope of killing him before he can destroy the Christ-child. However, one by one, Damien kills off all the priests (some in horrific circumstances) until only DeCarlo survives.Finally, in spite of Thorn's efforts, DeCarlo informs Reynolds that the Christ-child is out of his reach but that, nonetheless, the task still remains to destroy Damien. In hopes of getting her son back, she (deceivingly) agrees to take him to the Christ-child in exchange for Peter. This is actually part of DeCarlo's plan to lure him into a trap where he is hoping to ambush Damien and catch him off guard, since most of his attention would be directed towards confronting Christ.The plan backfires though when Damien manages to spot DeCarlo first and in a final act of evil, Damien uses Reynolds' son - now slavishly devoted to Damien - as a human shield against the dagger. As Peter lies dying, Damien partially strangles the stunned Father DeCarlo.In a desperate bid to salvage his waning power, Damien calls out for Christ to appear before him. As he does, Kate sneaks up behind Damien with one of the daggers and stabs him in the back, releasing an otherworldly reverberating wail of demonic agony throughout the cathedral ruins. Christ appears before a dying Damien who then mockingly tells Christ 'Nazarene...you have won...nothing'.After Damien dies, his body is seen lying on the ground with Kate standing over it. In the foreground, De Carlo carries Peter's body and hands him to Kate. The film ends with scripture of Revelation Chapter 21, Verse 4 indicating that when Christ returns to earth, peace will reign for all who faithfully awaited the Lord's return.