Robert and Katherine Thorn seem to have it all. They are happily married and he is the US Ambassador to Great Britain, but they want more than to have children. When Katharine has a stillborn child, Robert is approached by a priest at the hospital who suggests that they take a healthy newborn whose mother has just died in childbirth. Without telling his wife he agrees. After relocating to London, strange events - and the ominous warnings of a priest - lead him to believe that the child he took from that Italian hospital is evil incarnate.

Damien Thorn is dead, but his prophecy is reborn in a mysterious girl named Delia, who is adopted by two attorneys, Gene & Karen York. When Karen realizes her baby was born under suspicious circumstances, she hires a private investigator to find Delia's real parents. A series of bizarre accidents occur, and Karen begins to suspect everyone of conspiring against her as she unravels the truth about her baby.

Now come into his full knowledge and power, the Anti-Christ in the body of Damien Thorne is about to strike his final blow. The Christ-child has been born again, on the Angel Isle, Great Britain (Scotland, England & Wales). The plan is simple, find the male children born on the specified day, and kill them all.

Seven years later, 13-year-old Damien is just discovering who he really is, and what he is destined to do. Now living with his Aunt, Uncle, and cousin in a wealthy suburb of Chicago, Damien is anxious to inherit everything. Can Richard Thorn finish the job that Damien's father (Ambassador Thorn) started?

When the Vatican observatory priest sees the appearance of a comet, the Church is sure that it confirms the eve of the Armageddon. Meanwhile, the USA President's godson Robert Thorn is informed in the maternity in Rome by Father Spiletto that his wife Katherine has just lost her baby and she had troubles with her uterus and would not have another pregnancy. Spiletto suggests Robert that another just born child that lost his mother could be the substituted for his son, and Robert accepts the child and gives the name of Damien. Robert is promoted to ambassador in London after a tragic accident. When Damien's nanny commits suicide in his birthday party, a substitute, Mrs. Baylock, comes to work and live with the family. Along the years, Katherine realizes that Damien is evil, while Robert is contacted by Father Brennan, who tells him that Damien is the son of devil. When the priest dies in a bizarre accident...