Jonathan Glazer’s mesmerizing new feature, Under the Skin, bids the viewer to peer through the eyes of a monster. The creature in question has assumed the shape of a comely human woman, portrayed by Scarlett Johansson in a performance of breathtaking precision. The film intimates that this strange entity is extraterrestrial, but does not offer specifics as to its origin or nature. Indeed, Under the Skin is positively ruthless at withholding details that are incidental to the story’s fundamental needs. Glazer presents the viewer with the minimum information that is necessary to follow the film’s alternately prosaic and abstract narrative.

The mysterious woman appears to be operating under the direction of an outwardly male counterpart. Their ultimate purpose is never established, but their proximate mission eventually becomes dreadfully apparent. The woman prowls the streets and motorways of Scotland in an anonymous van, seeking solitary men who are easily inveigled into the passenger seat and thereafter into a squalid building. Within a black, featureless chamber, the woman entices them forward in erotic anticipation, even as the unfortunate soul sinks heedlessly into the semi-liquid surface underfoot. Encased within a murky prison, the victim is slowly digested until—with an abruptness that is downright nightmarish—bone, muscle, and viscera are torn from their bodies in an instant, leaving only a floating husk of skin.

Broadly speaking, Under the Skin‘s curious protagonist has qualities that could be regarded as vampiric. Like the nosferatu, she preys upon humans for their tissues, a harvest with not-so-subtle sexual undertones. Indeed, a glib description of Under the Skin could be “Stanley Kubrick’s Lifeforce”. Conceptually the film bears some resemblance to Tobe Hooper’s notorious exploitation classic about naked “space vampires”, but its chilly aesthetic is informed by the likes of Kubrick’s 2001: A Space Odyssey, A Clockwork Orange, and The Shining.

Nonetheless, Under the Skin‘s creature has a stronger resemblance to another famous monster, the siren of Greek myth. Although physical descriptions of this beast differ across Archaic and later sources, the siren typically possesses female attributes and a malevolent intent. Her most conspicuous characteristic is her entrancing song, a sound so exquisite that it can entice sailors to their dooms. Robert Fagles’ translation of The Odyssey vividly describes the sirens in terms that echo the horrific imagery of Glazer’s film: “lolling there in their meadow, round them heaps of corpses, rotting away, rags of skin shriveling on their bones.” The kinship between this mythic fiend and Johansson’s she-thing is such that the latter (unnamed in the film’s credits) might be simply dubbed the Siren.

The film’s screenplay is loosely adapted by Glazer and Walter Campbell from Michel Faber’s surrealistic science-fiction novel of the same name, a work that is more satirical in tone and much more explicit regarding the protagonist’s nature. The film subjects the traditional monster movie to a perspective flip, presenting the Siren’s encounters with humans primarily from her viewpoint. A lesser filmmaker might have used this reversal as a gimmick, a means to a shallow sort of revisionist alien abduction tale. Glazer achieves something more thoughtful, disquieting, and challenging. As in John Gardner’s landmark novel Grendel, seeing the world through monstrous eyes presents an opportunity for existentialist rumination.

In the film’s early sequences, the Siren goes about her tasks with agile efficiency. She chats up potential prey to determine whether they would be missed if they disappeared. When she deems a target unsuitable, her friendly demeanor vanishes as she pulls back into traffic to continue the search. The speed and exactness with which Johansson achieves this shift—from humane warmth to cold focus—is astonishing. It suggests that the temptress is merely a mask, and beneath it lies the resolute blankness of a prole. This can also be discerned in the way that the Siren’s come-hither routine evaporates the moment a victim sinks into darkness, leaving her to methodically gather the man’s discarded clothes.

Nonetheless, the film also presents telling moments when the Siren appears to be plagued by confusion and anxiety. She is occasionally taken unawares by human behavior, and at times seems stunned into inaction by the events around her. She stares in befuddlement when one potential victim bolts down a beach to save a stranger downing in the freezing pull of a riptide, as though such selfless imperilment were wholly foreign to her. She gazes at her own eyes in a mirror, perhaps seeking some answer to a nagging question, or a telltale flaw that will herald the end of her usefulness. (The latter is reinforced when her mute male overseer, outfitted in a motorcycle racing suit, also scrutinizes her eyes with his pitiless glare.)

The film’s turning point occurs when the Siren encounters a man (Adam Pearson) with facial disfigurements from neurofibromatosis. She successfully ensnares him by adjusting her tactics, voicing sympathy for his loneliness and complimenting his youthful hands. After the man sinks beneath the dark room, the Siren peers at herself in a dim hallway mirror for what seems like minutes. One can sense something rising to the surface in this long shot, and it abruptly breaks through in an unthinkable act of rebellion. The Siren releases her victim from his gooey imprisonment and then runs for her life.

The Siren’s treacherous actions neatly bisect Under the Skin into two parts that might be labeled Slavery and Freedom. Like Grendel, the film is entwined with the philosophy of Jean Paul-Sartre, and specifically with the pivotal concept that “existence precedes essence”. The former is illustrated in the Siren’s realization that she can define herself through her actions, that her seductress identity is not tied to some intrinsic quality imprinted in her flesh, but to her performance of that role. She can, at any time, choose a different role and thus become something else (the Not-Siren).

This freedom—an individual’s ultimate liberty to define themselves—is not without limits, as becomes agonizingly apparent in film’s second part. The Siren is still constrained by what Sartre calls facticity, the tangible details of her existence. She is penniless and alone in a society that she does not fully comprehend. (Post-liberation, she seems freshly infantile and bewildered by the world around her.) She discovers to her dismay that she cannot consume a slice of chocolate cake without retching, and that sex is perilous to her veneer of human flesh.

Moreover, her free state carries with it the terrifying weight of responsibility. This is true in the existentialist sense that she is “condemned to be free,” and therefore her fate ultimately hinges on her decisions, irrespective of external limitations. The Siren’s experiences also reflect the changes wrought by transformative socio-political movements such as feminism, postcolonialism, and Marxism. These offer a perilous kind of autonomy, a freedom from paternalistic forces (patriarchy, empire, capitalist) that exposes the liberated individual to unfamiliar threats.

Deprived of the protection and guidance of her masters, the Siren eventually stumbles into jeopardy when a logger attempts to sexually assault her in a remote forest. That this cruel encounter ends fatally for her does not imply that a state of self-imposed enslavement is preferable to freedom. Rather, it illustrates the inherent evil of systems that would impose a false identity on the individual. The Siren’s masters have a vested interest in keeping their charges ignorant and helpless, as it ensures that deviants such as her meet an ugly end. As disconsolate as Under the Skin‘s conclusion might seem, the film’s final shot, straight up to the zenith of a snow-filled sky, hints that the Siren is not alone in her epiphany. Elsewhere in the universe, there are countless other Sirens, and they will not remain bound forever.