Easily one of the most successful horror novels of all time, and one of the best known and most referenced films ever made, Rosemary's Baby more than made its mark on the horror landscape. In some ways, the book and film changed the game entirely, with both author Ira Levin and director Roman Polanski tapping into the cultural zeitgeist in a way that few have done before or since.
The differences between the novel and the film are mostly non-existent. Polanski studied the book somewhat obsessively, marking pages and engaging in long conversations with Levin about everything from story to wardrobe details. It wasn't Polanski's first film, but it was his first adaptation of an existing work and he seemed unaware of his right to make changes to the source material. What we get from this is one of the most faithful depictions of a book ever brought to the screen.
The story begins with Rosemary and her husband Guy moving into a new apartment. Guy is a self-absorbed actor, while Rosemary is a housewife who essentially transitioned from living at her parents' house to living with Guy, never knowing independence. Rosemary briefly meets another young woman named Terry, who wears a necklace filled with tannis root given to her by an elderly couple living in the apartment complex, the Castevets. Shortly thereafter, Terry appears to leap to her death from a window in the Castevets' apartment. The couple invites Rosemary and Guy to dinner and express brief, passing remorse for Terry, who they describe as being “like a daughter” despite barely seeming to notice she's gone. The Castevets are obtrusive and they offend Rosemary, while Guy becomes slowly more beholden to them as the weeks go by.
Meanwhile, Guy unexpectedly lands a major role in a play when the actor originally cast goes blind out of nowhere. While he's previously expressed apprehension about starting a family, he seems suddenly excited by the prospect and begins making plans with an elated Rosemary. One night, Rosemary eats a dessert prepared by the Castevets and begins to pass out suddenly as if drugged. This leads to a long, surreal rape scene, equally horrifying across mediums. To make it even more upsetting, when Rosemary wakes up covered in scratches, Guy takes credit, joyfully announcing that he had raped her in her sleep and presenting it as a somehow consensual act. Rosemary is, understandably, upset.
In the novel, if not in the film, Rosemary actually leaves Guy for a few days and considers leaving him for good. But over the course of her getaway, her anger dissolves to helplessness and forgiveness, and she goes back to her husband. The reason this part of the book is important is that it shows Rosemary's only true attempt at independence, however brief. Her attempt to take control of her own life makes it all the more tragic when she fails to do so later on. Without this scene in the movie, it's easy to see Rosemary as a bit of a lost cause from the very start, and her constant deferral to the wishes of the people around her until the bitter end becomes a bit grating. Not surprisingly, Rosemary's situation does not improve. Guy's behavior towards her changes, and as a result she becomes despondent and increasingly upset. Finally, she resorts to throwing a small party in their apartment for their younger friends, barring the Castevets against Guy's objections.
One of the most interesting moments of the movie happens during this party. Rosemary's close circle of friends draws in around her, locking Guy out of the kitchen and advising her to disregard the advice being given to her by her husband and doctor. This acknowledgment of the close circles of female friendships and how they operate is perhaps the only genuinely feminist moments in a film that sees its main character slowly tortured before ultimately embracing her “womanly duty,” despite significant reasons not to. Yet also realistic is Guy's lashing out about Rosemary's friends, calling them “not very bright bitches” before going on to berate Rosemary for choosing to see another doctor about the constant pain she's been experiencing.The moment of celebration over the very brief appearance of Rosemary's friend group quickly ebbs, and the triumph over changing doctors does as well. Rosemary's pain subsides and she seems to accept things as they are for a while. After the sudden death of a friend, she begins investigating the Castevets, deducing that their names are anagrams and they are related to prior residents of the apartment complex that were accused of practicing Satanic rituals. Rosemary starts to suspect that they are in league with the Devil, while Guy is helping them in exchange for a boost in his previously floundering acting career. Rosemary attempts to escape Guy and the Castevets' doctor, but goes into labor.
When Rosemary awakens, she's told that her baby died in childbirth, but she refuses to believe it, ultimately uncovering a secret door to the Castevets' apartment. There, she discovers her baby, named Adrian, who has the appearance of a demon. Many of the other residents of the apartment complex are gathered around the crib, and they explain to Rosemary that the child is Satan's, not Guy's. Guy excitedly tries to assure Rosemary that their next baby can be just theirs. Rosemary's horror fades to maternal pride as she begins rocking baby Adrian and humming a lullaby. Cute! It's... kind of cute.
The religious aspects of Rosemary's Baby are often noted, citing Rosemary's apprehension about her Catholic upbringing as she slowly swings towards a life of Satanism, dictated by the birth of her demon baby. Levin himself was an atheist, or at least a non-believer, and hoped his novel would increase skepticism around religion. It's hard to say if the book was successful in that regard, but Levin for one was fairly unimpressed by the reaction. It actually played some part in the rise of public interest in the occult, the apparent opposite of his intention.
Beyond its religious commentary, within both the book and the film adaptation of Rosemary's Baby is a story about gaslighting. Rosemary is consistently dissuaded from looking out for her own best interests and encouraged to go along with what is being suggested to her without question. The frustrating part of the story is that it's exactly what she does, bearing some semblance to Levin's Stepford Wives protagonist Joanna Eberhart five years later, as well as his Sliver protagonist Kay Norris in 1991. Levin didn't write that many books, but he did tend to lean heavily on female characters that wouldn't push too hard against the grain to make his points. If Rosemary had left her husband earlier on, the story itself would mostly fall apart.
It's not particularly fair to take Levin to task for his somewhat weak female protagonists, but it's also questionable to attribute too much credit to the idea that he was providing feminist commentary by fully showing their vulnerability while failing to give them much strength. Levin was a fantastic writer, and his style definitely draws the reader in, but often his characterization of men as being intrinsically devious and women as being completely susceptible falls a little flat. On the other hand, Levin does show a great deal of understanding towards his self-doubting, nervous female characters, humanizing them in a way that many writers over many centuries have failed to.