Both Rosemary's Baby and I Walked with a Zombie are movies that have explicit elements of what we might more commonly think of as "horror" films. On the other hand, however, both rely so heavily on atmospheric tension and are so laden with strange ambiguity and "arty" moments that they seem to transcend the genre. Given the large following behind both movies as well, they are often just as likely to be described as "cult films" as horror movies. Indeed, it is important to realize that what makes cult movies a genre in their own right is not simply a lack of box office performance or else a devoted fan following. Indeed, cult movies share many other characteristics and a most typically marked by an otherworldly strangeness and an overriding sense of oddity. Often, these films are controversial and in certain ways they seem to transcend their genre in ways that ordinary or "mainstream" films never would. Both Rosemary's Baby and I Walked with a Zombie manage to do more than typical films of the horror genre and deal with controversial issues beyond the scope of most such films. At the heart of both of these pictures is a conflict between Western, empirical, rational modes of knowing and more "primitive" magical means of viewing the world. The conflict between these two modes is not resolved quickly or easily, however, and the ambiguity surrounding which mode of understanding is the correct one is very much what gives these films their narrative tension. By relying heavily on this ambiguity both movies create a sense of dramatic and narrative tension that amounts to a general anxiety or paranoia. It is in their use of this ambiguity to induce a sort of paranoia in their viewers that these two films realize the element that makes them true "cult" films, because both possess a strange relationship with their viewers that the average film would strenuously try to avoid.
Cult films are typically films that failed to do well when they initially appeared a the box office, but nonetheless managed later to develop a rabid and appreciative fan base that is very much obsessed with the film and views it repeatedly (hence the semi-ironic use of the term "cult" in cult film). The definition of a cult film, however, is not limited simply to these elements of typically poor commercial performance and an ensuing body of intense fan support. Indeed, cult films typically possess other common attributes that define them as cult films rather than mainstream productions:
Cult films are usually strange, quirky, offbeat, eccentric, oddball, or surreal, with outrageous, weird, unique and cartoony characters or plots, and garish sets. They are often considered controversial because they step outside standard narrative and technical conventions. Most cult films cut across many film genres (science fiction, horror, melodrama, etc.), although they can be very stylized, and they are often flawed or unusual in some striking way.
Indeed, it is in these oddball and controversial moments where cult films typically find both the elements that connect with fans and where their most interesting moments lay. It is also in these controversial and strange aspects that the argument for cult films as genre becomes coherent; cult films are a genre precisely because of their tendency to mix genres in strange ways and to explore unusual and difficult themes that most "mainstream" films would not touch with a proverbial ten-foot pole. It is in these aspects of the cult film that both Rosemary's Baby and I Walked with a Zombie find their sympathetic resonance.
Both of the films have a similar approach to the way that they create dramatic tension -- and the sort of dramatic tension that both films create is at once intriguing, unusual, and strangely captivating. Both films, in the tradition of good horror films/scary movies, begin with eerie settings. Rosemary's Baby uses a tenement building in New York that has a strangely "haunted" past involving the use of witchcraft. I Walked with a Zombie on the other hand uses the island of St. Sebastian with its history of voodoo that is imbued with "primitive" animist beliefs. These elements create a tension right form the very start, because they foreshadow something grim, grisly, and terrible, but the actual knowledge of what the terrible thing to come will be is left fundamentally unclear. This ambiguity creates a strange and general anxiety in the viewer who is made, by this ambiguity, to feel concerned, but to have no specific object on which to direct his or her concern. The result is the development of a feeling of general anxiety in which every moment in the film and every speech is loaded with the possibility of a horrible meaning that lies just below the surface of what appears to be "normal." In this manner, both films construct a dramatic tension that is based largely on a generally anxiety that quickly comes to resemble paranoia -- every character in the film comes to be possibly implicated as part of "the plot" against the protagonist. In these two films, the ambiguity is actually even constructed in a more specific way. Rather, the ambiguity is then directed towards a specific question that is not resolved until the culmination of the films.
In both movies the ambiguity moves from an early general anxiety to an ambiguity that is focused more specifically around resolving on single puzzling issue. In the case of Rosemary's Baby, one of the central concerns becomes not just what the plot against Rosemary is per se, but whether indeed her ideas that she has been impregnated by the devil are in fact correct and real. Certainly, there are a series of terrible and strange circumstances leading up to it, such as Rosemary's interaction with Terry, a woman living on the street who has been taken in by the Castavets. Indeed, it seems odd that they would take her in for any altruistic purpose, and her subsequent suicide only serves to cast a further suspicion over them. Thus, while on the one hand we as viewers are inclined to side with Rosemary in her belief that the Castavets are members of a coven who are trying to impregnate Rosemary with the Devil's baby, on the other hand we are confronted with deeply incomplete, subjective, and ambiguous evidence for this claim. Even Rosemary's experience of her "impregnation" by the devil is exceptionally hallucinatory and unclear such that we cannot be certain whether this impregnation is the "real" work of black magic or else a deeply felt and imaginative hallucination on the part of Rosemary. Certainly, we as the audience want to believe her and can't imagine why she would want to have such a terrible hallucination, but if decide to believe her we must do so in the face of all of our industrialized Western scientific concepts. Here then, although the ambiguity is focused more specifically on one question, whether or not Rosemary is "actually" carrying the devil's baby, the ambiguity still has the effect of creating a general anxiety and paranoia because of the question's very centrality. In effect, our whole understanding of the action of the film depends upon the answer to this question. If Rosemary is correct about her baby being the devil, then we must feel for her as the victim of a terrible plot. If it is a hallucination, then she is pathetic and insane character, not a heroic one. Thus, this question still creates a feeling of paranoia, because we literally cannot be certain of our feelings about anything in the film without knowing the answer to it.
A similar question arises in I Walked with a Zombie over whether or not Mrs. Holland is in fact a zombie. The question arises early and is not put to rest until the very end of the film. Indeed, Betsy, as a nurse, is effectively an emissary of Western scientific medicine, who has come to a "primitive" magical place. In this very move, the film reveals that it, like Rosemary's Baby, is deeply intrigued by the clash between a Western belief in measured rationality and a more primeval, irrational, magical force beneath things. In one notable scene, this clash is bought to the forefront by the disparity between what Mrs. Rand says about Jessica being a zombie and the voodoo priest who has been "testing" her. Mrs. Rand offers an explanation for Jessica's state that would be more consistent with the practice of rational Western medicine. Indeed, both Betsy and we as the viewers would like to believe this description, but doing so becomes increasingly difficult when we are forced to consider the "tests" performed on Jessica by the voodoo priest to see whether or not she is indeed a zombie. Indeed, the voodoo priest discovers that unlike most human beings, when he pricks Jessica, she does not bleed at all. Even more disturbing is that he is able to control Jessica's movements through the use…