The last thing Rosemary Woodhouse remembers is trying to escape the Bramford to save her seven-year-old son Andrew from the grips of a Satanic cult that planned to rear him as the Antichrist and use him to conquer or destroy the world. The year was 1973.
She awakes abruptly in a long-term care facility, a mystery patient with no name, in 1999. Her coma was caused by the cult and ended the moment its last member died. Desperate to learn what became of her son, she discovers that he has become the charismatic founder of a wildly successful world-wide charitable organization that has managed to nearly eradicate hunger, poverty, and disease. Mother and son are reunited, and Rosemary herself achieves celebrity as the long-lost mother of the most beloved and respected public figure in modern history. Rosemary feels relieved that Andy has successfully cast off his diabolical lineage and devoted his life to achieving world peace.
And then, on New Year's Eve at the dawn of the new millennium, everything goes horribly right.
Published thirty years after its predecessor, and the final published work of its author, the book was considered a critical failure and a disappointing ending for both the author's career and the well-respected original, with some critics wondering aloud if the sequel might have been a Contractual Obligation Project meant for the author to retain control of his intellectual property before the publishers contracted a ghostwriter to create an unwelcome sequel for him. In any case, the ending of Son of Rosemary so radically alters the events of Rosemary's Baby that many fans of the original work prefer to pretend the sequel never happened.
Provides examples of:
- All Just a Dream: Rosemary seemingly awakens from sleep thinking it was All Just a Dream — that's the entire story, first book and sequel. In the final paragraphs, though, it turns into Or Was It a Dream?? Rosemary's friend Hutch telephones, and at the very end of the conversation he casually tosses off how long it took him to solve "roast mules" (see Arc Words below). This tells Rosemary that everything that happened in her "dream" was real, that her now-nonexistent son has pulled off the ultimate sacrifice to save the world, and that she'd better be damned careful about where she and her husband move.
- Anti-Antichrist: Satan-sired baby Andy has grown up to run a global charitable foundation, and claims to be struggling to cancel out his evil side by doing good. Descendents of the cult from the first book seek to undermine his attempts to Screw Destiny and be a good man. In the end, his mother wakes up in 1965, to find that her child's conception and entire life were All Just a Dream. It's implied that Andy pushed the Reset Button on the world, re-writing history, once his full powers as the Antichrist manifested, so he wouldn't have to bring on the apocalypse.
- Ambiguous Ending: Did Andrew restart the world in order to save it? Or did Rosemary dream the events of both books? If her dream is prophetic, will she be able to change history, or will events play out as they did before?
- Arc Words: Throughout the book, various characters josh around about how long it takes to solve the riddle "ROAST MULES" with the clue "Any five or six-year-old might do this every day." The answer is somersaults.
- Biological Weapons Solve Everything: How Andy's organization plans to bring about world peace.
- Comatose Canary: Rosemary fills this role in the time between Rosemary's Baby and Son of Rosemary.
- Humans Are the Real Monsters: Though Andrew's organization has been able to greatly reduce poverty, world hunger, disease, and war, Andrew is frustrated that he cannot completely eliminate them, and has come to the conclusion that no amount of charity and good will is great enough to overcome the misery caused by human nature.
- Missing Mom: What Rosemary has been for Andrew all this time.
- Religious Horror: Religious scholars have noted that the portrayal of Andy as a universally adored Antichrist who promises and delivers tangible benefits to mankind is more accurate to scripture than the portrayal of a malevolent, tyrannical Antichrist in the Christian series Left Behind published a few years before.
- Retcon: The final pages of the book completely change the context of Rosemary's Baby.
- Rip Van Winkle: The novel Son of Rosemary brings the heroine of Rosemary's Baby up-to-date by having her awaken from a twenty-plus year sleep, just as her demonic son's plotting to bring about The End of the World as We Know It.