Earlier this year, I wrote about the studious neoclassicism that sometimes seems to petrify the current French cinema. But the new French film “Planetarium” (which opens today), starring Natalie Portman, suggests that, in the right hands, there’s an upside to such an absorption in the movies’ grand tradition: the power to reëxamine it, as if from within. “Planetarium,” directed by Rebecca Zlotowski, who wrote the script with Robin Campillo, is a glossy historical fantasy, loosely based on a true story—and its glossiness is essential both to its evocation of the past and of its setting, the French movie industry of the nineteen-thirties.

Portman, speaking both French and English, is the star, and her character, an American woman named Laura Barlow, is the center of the action, but she’s not exactly the movie’s protagonist. Rather, that would be André Korben (played by Emmanuel Salinger, who’s among the most calmly and compactly expressive of modern actors), a film producer and studio boss in his mid-forties who’s looking vigorously ahead to the future of the industry and the art of the movies while getting caught in the pull of his own past. Korben is loosely based on the real-life producer Bernard Natan, a Jewish émigré from Romania who took control of a major studio but, in the wake of an anti-Semitic campaign, was hounded from the job in a trumped-up sex scandal, imprisoned, and ultimately deported from France to Auschwitz, where he died. (David Cairns and Paul Duane’s excellent documentary, “Natan,” from 2013, looks deeply into the producer’s life and the charges that he faced.)

The real-life Natan’s innovations included efforts at television and wide-screen filmmaking, as well as an early adoption of sound. In “Planetarium,” Zlotowski adds a splendid twist to the producer’s cinematic passions: the fictional Korben, haunted by his past in Romania, by the family that he left behind, and by the dead, witnesses a performance by two American mediums, Laura and Kate Barlow (Kate is played by Lily-Rose Depp), and Korben decides to bring them into the movies. His plan is multipronged: first, he schedules private séances with them (and it turns out that the elder sister, Laura, is more the front person, the personality of the act, whereas the adolescent Kate is the actual conduit to the spirit world). Soon, he draws them into his circle (even puts them up in his home) and tries to turn Laura into a movie star. Then, he fuses his two passions, for movies and for his own haunted visions, and invests heavily in the invention and development of a camera that will film apparitions, spirits, ghosts. Korben wants to be the first filmmaker to capture physical, visual evidence of the metaphysical realm—and the ghosts that he wants to capture on film are his own.

The visionary side of this quest for the supernatural also involves a mysterious Polish visitor who offers Korben the use of some peculiar equipment—a helmet of glass and metal that will capture Kate’s ethereal emanations—that goes into the producer’s cinematic experiments, too, and shifts them, and also Zlotowski’s film, into the realm of hectic science fiction. Korben and the Barlow sisters talk of ghosts with a trenchant, tender romanticism akin to that of “A Ghost Story,” but Korben’s ghosts aren’t merely intimate—they’re ghosts of his Romanian past, of his Jewish childhood, of the Jewish identity that he sacrificed when he came to France, changed his name, and changed his life.

“Planetarium” offers a vision of the pain of the past as if through a thick sheet of glass. The actors’ gestures are smooth, their diction is precise, and—though the movie is neither slow nor sluggish—it has a behind-the-beat tone, with hesitations and silences, fixed gazes, etched aphorisms, resolutely gliding images to match, that suggest a sort of time lag in the transmission of the past to the present, the distance and the strangeness of the past preserved, as if in an amber that hasn’t yet hardened. (It’s stylistically reminiscent of Alain Resnais’s “Stavisky,” his 1974 drama about another real-life nineteen-thirties French financial scandal involving an anti-Semitic campaign.)

Zlotowski takes obvious pleasure in dissecting the day-to-day details of movie production and film financing: the preparation of actors in a studio dressing room; the rituals of screen tests and the strategies of directors working with actors as film burns like money through the camera; the deadly serious frivolity of parties where decisive connections are made or decisive relationships are broken; high-pressure performances in front of a room of shareholders and high-pressure backroom and studio-corridor decision-making, with movies, careers, and dreams hanging on the strength of a yes or a no. She also takes a grim documentary pleasure in revealing the ugliness, the calumnies, the prejudices that poison the industry precisely as a result of the financial and societal stakes that are at play in movies.

Portman’s performance as Laura is her best (or the best of hers that I’ve seen) since “Black Swan,” because Zlotowski catches something in her bearing that only Darren Aronofsky has made such similarly good use of—the expressive power of her masklike stillness. Laura is a public figure, a stage presence but an extraordinarily cool one, whose hold over an audience, mediating between Kate and her subjects, is achieved with a minimum of gesture, inflection, and show. That persona is continuous with her offstage personality, and it conflicts, subtly, comically, with the overkilled dramatic performances that Laura is directed to give in popular French movies of the time. In effect, Portman is playing a mediocre actress, or, rather, an actress rendered mediocre by mediocre direction—an actress awaiting the kind of direction that would bring out her authentic power.

There’s a tense calculation behind Laura’s tense manner—a pretense without end. She’s a showperson whose life onstage and, eventually, in movies is strictly professional; she had no movie ambitions, and she sees Korben’s interest as a payday and also as a chance for adventure. Kate, for her part, is at least persuaded of the authenticity of her own visions; the séances in which she coaxes the spirits from Korben’s repressed memories and closed-off soul have a fury that ranges from convulsive to orgasmic—but they don’t translate to movies. (As it turns out, they transfer strangely and painfully to her life.) Among other things, “Planetarium” is a free riff on the very nature of cinema and of performance, on the paradoxes of fiction and documentary, of what an actor gives and what a camera captures.

For all of its virtues and distinctions, “Planetarium” isn’t a comprehensive experience; it’s a teeming and gleeful grab bag of deft cinematic flourishes. The movie realizes history only anecdotally and does little with Korben’s memories, past, and inner identity. The political pathologies of the time crop up in hints and touches that feel thinly researched and analyzed. Nonetheless, as a story of ghosts and the effort to film them, of France’s own ghosts and their repression, of the deadly threads that link the industry today and, for that matter, the government and French society at large to a time that’s both ubiquitous in memory and increasingly inaccessible to experience—and as a vision of an aesthetic and an industry that depends upon and remains linked to their own often dubious, often destructive past—“Planetarium” is a rueful delight, a living reproach to any neoclassicism less self-critical and self-aware than its own.