It’s not exactly a cinematic mystery on par with “Rosebud,” but the coup de grace of Luis Buñuel’s 1967 film “Belle de Jour” has always been a powerful secret — and a taunting, sadistic twist to puzzle over. As Séverine (Catherine Deneuve), a wife who secretly spends her afternoons in a brothel, looks on, her husband’s best friend Henri Husson (Michel Piccoli) whispers something in his ear. Henri, who frequents the same brothel, has tormented Séverine by threatening to reveal her secret — an act whose cruelty is made nearly sublime since her husband is now a paraplegic confined to a wheelchair. But Buñuel never reveals whatever it is that Henri has said.

That moment has stayed with the great Portuguese filmmaker Manoel de Oliveira ever since, and, at age 98, he pays homage to the surrealist masterpiece by imagining the same characters — Henri and Séverine — nearly 40 years later. At just over an hour, “Belle Toujours” is more of an extended vignette — a riff, really — on the earlier film’s themes, and, ultimately, a meditation on old age and the strange currents of passion.

Henri (played again by Mr. Piccoli), by all appearances a dignified, well-tended gent, is at a symphonic performance of Dvorák when he spies Séverine across the way. Séverine is now played by Bulle Ogier (in a blond wig), a ploy that slyly references Buñuel’s “That Obscure Object of Desire,” in which the female lead was played by two different actresses.

Here, Ms. Ogier’s Séverine does her best to become obscure. She catches Henri gazing at her, and quickly slips away into the Parisian night as the concert ends. What follows is a bit of situationist folly, as Henri turns stalker. Unable to spot his prey, he visits a small bar where he believes she may be. He begins to tell his tale — and the original story’s sadomasochistic fantasy — to the bartender, as a pair of prostitutes (one old, one young) admire them both.

Turns out, the ladies know where to find Séverine, and soon Henri is off to her hotel. A game of cat-and-mouse ensues, and Henri returns to the bar for more whiskey, a satyr unsated. Again, he regales the boyish bartender with his exploits, indulging in some decidedly perverse (and French) boudoir philosophizing. The whores look on in their leopard-print garments, failing to win Henri’s affections (he dispatches them with a round of drinks) but serving as an echo of the brothel girls and madam of Buñuel’s film, and amplifying the voyeuristic tone.

It is pleasing to sit in with Mr. Piccoli as he reincarnates the kind of bourgeois archetype he played so splendidly in Buñuel’s films: well-fed, self-satisfied, with a twinkle in his eye and a touch of evil in his heart. Even if his best days are done, as the older whore comments, he possesses appeal. He has an appetite.

Mr. Oliveira takes his time to whet ours. The film is almost entirely a preamble to the brief dinner encounter between Henri and Séverine, who finally gives in to her former blackmailer’s insistent pursuit. Thanks to a measured pace, and long, static shots that often capture the actors as if from a window across the boulevard, we linger in Henri’s head like the hangover all those whiskeys must cause him. Even without that much dialogue (the film could easily be a stage play in a black box theater way off Broadway), Mr. Piccoli saturates the screen in his act of recapturing the past.

What happens when Séverine comes to his rich man’s townhouse for dinner? As she tells him, “I’m another person now.” Another joke, in a way, since this Séverine actually is. Whatever Henri expected, she’s insistent to thwart it, and yet, she needs to know exactly what he told her now-deceased husband.

What happens next has less to do with “Belle de Jour” and everything to do with two actors making the unspoken feel richly indelible. Mr. Oliveira’s touch may be light, but it has the crisp effect of a quick slap to the face.