François Cluzet and Bérénice Bejo in The Man in the Basement (Caroline Bottaro/Greenwich Entertainment)

Philippe Le Guay’s taut thriller is about a subject all too relevant today: denialism. The last few years have brought us election and Covid vaccine deniers to add to the conspiracy theories that reject historical events such as the Holocaust, which is what Le Guay’s film centers on.

Simon Sandberg, a construction manager, shows Jacques Fonzic, a retired schoolteacher, the unfinished cellar in his family-owned apartment building that’s up for sale as a storage space. (Simon tells Fonzic selling this will pay for a new kitchen for him.) Simon and Hélène, his wife, agree to let Fonzic purchase the basement. They give him a key, and he starts moving in his belongings.

Not long afterwards, things start to go awry as Simon realizes that Fonzic is actually living in the cellar—he uses the restroom of a bar down the street, and its Arab owner tells Simon that Fonzic has yelled racist slurs at him. Simon graciously offers to let the retiree stay in the family’s guestroom in the apartment complex. Then Simon discovers that Fonzic is a Holocaust denier, or as the buyer calls himself, “a researcher,” which is the reason he lost his teaching job.

Simon avoids leaning onto his Jewish heritage (at one point he says, “I don’t want to get hung up on the past”), but this revelation is a bridge too far. Arriving late for a meeting with Fonzic, Hélène, and their lawyer to finalize the sale, he runs in and states that Fonzic will not be able to purchase the basement. However, Fonzic points out (and the Sandbergs’ lawyer confirms) that the law is on his side and their agreement is legit. Fonzic will not move out of the basement.

Director Le Guay turns the screws on his protagonists, as Fonzic becomes more entrenched in his position and starts receiving sympathy from others who live in the complex, even those who were not too thrilled when he first arrived. This is where the film begins to falter. At first, the slow recognition that Fonzic is not just an odd old man but a danger to others for his repulsive ideas and beliefs works convincingly, until Le Guay starts adding contrivances to speed up the dramatics, which often spill into melodramatics.

When Simon starts receiving dozens of unhinged emails from Fonzic that are racist and anti-Semitic, it’s creepy. But when Simon leaves the apartment one morning and finds a star of David and “Jew” scrawled in chalk on his front door, he runs back in to get a rag to erase it, so when he files a complaint at the local precinct, the officer rightly questions why he would get rid of evidence. His answer—so his wife and daughter wouldn’t see it—rings hollow.

Then there’s Simon and Hélène’s intelligent but naïve teenage daughter, Justine. She first meets Fonzic in the courtyard, and he engages in small talk about her history class—he was a history teacher, he tells her, and mentions that she should research the 12 million Native Americans who were slaughtered in the American West for a paper she’s writing. Her parents warn her about him, and she initially keeps her distance. But he keeps popping up wherever she goes, ever more improbably, and—after she gets a friend to spill her meal on him at a fast-food restaurant—he starts insinuating himself into her good graces, especially after she discovers he’s a widower and he gives her an ointment for the bruises she received while practicing martial arts.

Although it often stumbles—culminating in an ambiguous final shot that seems tacked on after much clumsy storytelling—The Man in the Basement nevertheless remains an effective glimpse at ingrained racist ideology, forcefully acted by Jérémie Renier (Simon), Bérénice Bejo (Hélène), François Cluzet (Fonzic), and Victoria Eber (Justine).