‘The Unknown’ Review: A Man Becomes Léa Seydoux After Having Sex with Her in Beguiling Thriller

Cannes: A hypnotic, vertiginous, Antonioni-flavored body swap movie from the co-writer of "Anatomy of a Fall."

At its most basic level, Arthur Harari’s “The Unknown” is a mesmeric, Antonioni-flavored modern thriller about a sentient STD of unknown origin (think: “It Follows”) that makes people swap bodies with their partners — more accurately thought of in this context as prey — during sexual intercourse. The mechanics of how that works are deliberately opaque so as to further ensure this film can be read in an infinite number of semi-legible ways, but allow me to walk you through the clearest example we’re given.

A hollowed and lonely Parisian photographer named David (Niels Schneider) goes to a raging costume party with his friends, where revelers obliterate giant piñatas shaped like all of today’s most hated right-wing autocrats — the Trump one explodes from the neck in a torrent of red confetti. Later in the evening, David makes eye contact with a woman he recognizes but doesn’t know (Léa Seydoux), and finds himself pulled into her gaze as if by a tractor beam. 

David follows the woman into an empty backroom, where she wordlessly mounts him without a condom. Neither one of these people appears to be enjoying themselves, but the woman soon begins to grunt with the bestial upset of a werewolf under a full moon. When David, febrile and seasick, wakes up in his flat the next morning, he has transformed into that woman — Eva. Or, at least, his essence has been spirited into her body.

The intricacies of that distinction will loom large over the beguiling film that follows, even if its characters are loath to discuss what they mean. In the short term, David — now played by Seydoux, of course, whose body language is suddenly as hunched and frantic as a child trying to  — is less concerned with parsing the meaning of his new body than learning the whereabouts of his old one, which was possessed by the entity the moment he vacated it. 

The good news is that it doesn’t take David all that long to find it hungry and unhoused under a local bridge. The bad news is that his body now belongs to a young woman named Malia (played for a scene or two by Lilith Grasmug before she’s targeted by the entity and forcibly ejected into David’s skin and bones), who’s understandably terrified about her present circumstances, and perhaps even more so at the thought of trying to explain them to her loving father (Radu Jude, radiating deep and powerful waves of papa bear energy in a climactic sequence that sees him slingshot from heartbroken rage to soul-quaking uncertainty in the span of just a few shots). 

And so David, presenting as Eva, and Malia, presenting as David, join forces to stay alive and get to the bottom of things. Unfortunately for them, “The Unknown” is reluctant to part with its mysteries. Adapted from “The Case of David Zimmerman,” a graphic novel that Harari co-created with his brother Lucas, the film is as protean and prone to shapeshifting as its characters — more so, actually, as the entity peaces out of the picture forever once it’s done with Malia, and the visceral body horror of forced displacement soon gives way to the more abstracted fear of losing oneself altogether. 

Our heroes do embark on some light sleuthing to find others who may have experienced the same phenomenon, but for the most part, they woozily drift around France and suffer the isolating dysphoria of feeling alien to oneself. Trans readings of the story are necessary (particularly from trans critics), and while “The Unknown” is too enamored by its own amorphous form to cleanly support any single explication, its script, which Vincent Poymiro co-wrote with the original authors, shoehorns in a tense moment at a public bathroom to signal a certain self-awareness. 

Gender distress plays a more pronounced role in the film later on, as two crucial scenes frame it as the insurmountable obstacle that prevents the entity’s targets from returning to a version of their previous lives. It’s here that “The Unknown” most acutely broaches the matter of how change is perceived — both within ourselves and in the world around us. Entire city blocks are erased and redrawn like an Etch-a-Sketch without anyone changing the addresses (as David illustrates in a photography project that chronicles how Paris has transformed over the last 100 years), and yet some people refuse to accept that something as mutable as a person might present in different ways over the course of a single lifetime. David and Malia struggle to accept that within themselves.

Of course, it would also be possible to see this as also a film about people who transition — or transform — against their will and spend most of their energy trying to reverse the process, and it’s not untrue that David and Malia mostly seem to acknowledge their new bodies out of disgust. David’s curiosity is limited to a sniff of an armpit and a peek at their vagina, while Malia understandably rues the fact that being transformed into a 40-year-old man has taken two decades off their life.

The subtle arcs by which these characters grow to become more comfortable in their new bodies — or don’t — provide “The Unknown” with the sense of progress that its discursive plotting and gauzy tone work to resist at every turn, as Seydoux and Schneider are both excellent at charting the liminal micro-expressions of their beings. (Schneider is especially convincing in his evocation of a young girl who’s even more fragile than they appear, his performance at once both a fantasy and a nightmare of self-negation.) Sex plays a surprisingly minimal role in this movie, given the supernatural STD of it all, but there’s an excellent bit of acting where Seydoux — as David — reacts to a creep’s advances in a way that discernibly reads like the reaction of a straight man who forgot that he was in a woman’s body. 

That small moment proves disproportionately instructive to the film’s prevailing ethos, which is most interested in bodies as vehicles for tracing the friction between fluidity and permanence. For better or worse, Harari uses gender dysphoria as a conduit to his more immediate concern: The idea that who we are is ultimately a memory that we share with ourselves.

Indeed, “The Unknown” is a film that’s pregnant with all sorts of ideas, most of them diffused through the lens of a slippery paranoid thriller that hypnotically sublimates its themes of transformation and erasure into every widescreen shot and piano note of Andrea Poggio’s sotto giallo score (or The Weeknd’s “I Feel it Coming,” for that matter). It arrives at its strange but satisfying destination with much the same entropy as everything else develops in this world, fulfilling David’s hope to “show what has disappeared,” and to do so by creating flashbulb images that viewers might hold onto long after other parts of themselves have shed away.

Grade: B

“The Unknown” premiered in Competition at the 2026 Cannes Film Festival. Neon will release it in theaters.

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