Claire Denis’s new film, “Let the Sunshine In,” which opened last Friday, is a very simple story of an enormous complexity. It’s a romantic comedy and drama in which the questioning of those very categories is a part of the action. The movie stars Juliette Binoche as Isabelle, an artist living in a gentrified, once-industrial part of Paris, moving ahead in work (including a new agreement with a prominent gallery owner) and tangled up in love. It starts with Isabelle and a lover naked in bed, a corpulent man heaving and thrusting on top of her, but even here, where the action is incontrovertibly physical, the scene is shaped by the dialogue, which lands with the pugnacious power of smacks.

The man, Victor (Xavier Beauvois), is a wealthy banker; she begins to find their relationship disgusting and, though his disgusting traits are part of his appeal to her, she breaks it off vehemently and moves on. She becomes romantically involved with an unnamed actor (Nicolas Duvauchelle); an ex, François Mandelbaum, whom she keeps inviting back (Laurent Grévill); and a rough-hewn man named Sylvain (Paul Blain), whom she meets dancing in a night club. Isabelle’s life leaps ahead, from adventure to adventure, from encounter to encounter, with an ironic abruptness. Her relationships, though physical (and Denis doesn’t shrink from depictions of sexual behavior), pivot on fine emotional points of an exquisite yet piercing hilarity—on the edge of humor and pain—and they’re developed largely through dialogue, which is the heart of the film.

Denis co-wrote the script of “Let the Sunshine In” with the novelist Christine Angot; it’s filled with sharply revealing and loftily aria-like dialogue, and Denis invents a form that seems to frame the discourse as if the images were a sort of operatic music. The dialogue of the film takes place at two levels throughout—it’s performed by the actors and pertains with an intense psychological specificity (and complexity) to the movie’s characters, who are rendered, as a result, exceptionally vivid and present even in fleeting appearances. But that dialogue is also a constant flow of mental and emotional energy, a seeming plasma that circulates around, among, and through the characters (and through Denis, Angot, the actors, and the crew—through the world of the film itself); that intense dynamic flux is as much the motor of the film as the specific traits and plans of characters. That’s why, for all the talk, and for all the psychology, “Let the Sunshine In” has a fierce, urgent physical power throughout, and why, for all its keen emphasis on the dramas of its characters, they seem to be part of a wider world throughout and Denis herself seems almost physically present in that world; if there’s a film where “the word made flesh” were the slogan of an artistic principle, this is it.

Isabelle’s relationships are complicated, and their turmoil sparkles with comedic confusions at many levels, from the blithering unintentional self-contradictions and repetitions to the higher ironies of happy accidents. She leaves the banker and gets involved with the actor, who then wishes that he hadn’t, that he’d waited. (Denis cuts from Isabelle’s gauzy, dreamlike, post-coital rapture to the actor’s slap-like declaration, into the camera, as if from Isabelle’s point of view, that he thinks they shouldn’t have rushed into a sexual relationship.) She occasionally has sex with the white-haired and stubbly-bearded François, but doesn’t want to get back together with him—yet she’s also prepared to break off a working relationship with her new gallery dealer over a rumor that François had had an affair with her. François is also the father of their daughter, Cécile, who’s ten, and who functions in the film as a brilliant ellipsis. Cécile’s near-total absence provides a nonsentimental view of motherhood—she’s seen only briefly, waving to Isabelle from the back seat of François’s car, but she’s nonetheless a crucial lever of power that François uses in his coercive dealings with Isabelle.

While on a weekend jaunt to a friend’s country estate (giving rise to the movie’s most sublimely frenzied comedic inspiration, Isabelle’s tirade against a rich man’s vain pride in ownership), she meets Sylvain, a man from a working-class milieu. Isabelle lives in freedom and comfort, she frequents the beau monde; she displays a warm personal interest in people from other backgrounds. But when Sylvain comes into her life, Denis doesn’t stint on or soft-pedal Isabelle’s own trouble forming an authentic, nonjudgmental bond with him.

“Let the Sunshine In” is also a peculiarly insightful glimpse into the emotional fluidity within the formal boundaries of French culture, which differs drastically from the sharp boundaries within the supposed fluidity of American life. In particular, lines between work and personal life that are flaming red in American life seem not to factor in Isabelle’s world, as in a scene in which she goes backstage to a theatre for a meeting with the unnamed actor. They’re meeting about an unspecified project; he soon complains about his work, then explains that his marriage is ending, goes into detail on his conflicts at home, and adds that it’s “fortuitous” that he met Isabelle just then. Though she looks increasingly panic-stricken and draws the conversation back to their project, she also suggests that they get dinner and, after an extraordinary set of push-and-pull passive aggression and rope-a-dope verbal wrangling, she invites him back to her home, where, along with sex, they have an extraordinary meta-conversation about the conversation that they’re not having.

The movie’s abrupt transitions, characters’ sudden appearances and disappearances, dialogue that picks up and drops off midstream, actions caught on the wing and abandoned en route, create a jolting sense of daily life as an effort to dance on a balance beam being shaken by beloved clowns. Yet the movie’s mercurial haphazardness has a sense of overarching inevitability, an emotional logic that turns Isabelle’s character, her inner life, into a dramatic structure in itself. The rhythms of “Let the Sunshine In” are those of screwball comedy, but the emotions are those of a bare-nerve vulnerability. The film extends beyond the bounds of its intimate action to conjure a vast, resonant, overarching vision of a world at large, of the times as filtered through a single consciousness and its unconscious overtones, emanations, reverberations, and premonitions. That air of metaphysical order crystallizes in Denis’s brilliant, near-quarter-hour culminating scene of Isabelle’s visit to a clairvoyant, played with a gruffly arrogant self-assurance by the ferocious Gérard Depardieu, who tells Isabelle’s future (and offers her a vision that involves the movie’s actual French title, “Un Beau Soleil Intérieur”—A Beautiful Inner Sun). He also offers her a final word—the English word “open”—which, in a way, retrospectively orients the movie’s disparate details.

For Denis, character traits aren’t limits or definitions but springboards for ardent observational curiosity. In a scene at a bar with Isabelle, Victor brazenly displays his assholishness in his curt, condescending, and punctilious orders to a young bartender, but Denis doesn’t pin him to the wall with it—she derives a wry pleasure from watching him overmanage the event (“gluten-free olives”) and devises a puckishly simple yet exotic visual strategy to film it (a pendular camera move that arcs back and forth around Victor and Isabelle) and tops it off with a crude sexual stinger. In bed with François, in the midst of playful and tender mutual pleasure, Isabelle is jolted by—and challenges and mocks—his unexceptional new sexual move that Denis’s camera (wielded by the cinematographer Agnès Godard, her longtime collaborator) picks up as if with a sly wink.

The film is very loosely inspired by Roland Barthes’s “A Lover’s Discourse,” the original title of which is “Fragments d’un discours amoureux.” The time frame is fragmented, leaping and lurching ahead in time and around in space. The variety of scenes offer fragments within fragments of discourse, with ingenious, impulsive dialogue spliced with things overheard and remembered, shooting off into unexpected directions like fireworks. Binoche’s performance, as Isabelle, is largely responsible for unifying the film’s wildly diverging impulses with a solid core of calm and purpose. Her expressions are more than mercurial—they’re multilayered, with laughter and tears, tenderness and fury, confidence and bewilderment flowing together and coexisting in plain and simple moments of an iridescent mystery. Few films of such precisely and intricately calibrated effect feel as free, loose, and swingy.