For nearly three decades, critics have argued over whether Catherine Deneuve's performance in the fascinating and troubling "Belle de Jour" is a career highlight because she delivers such a magnificent performance, or whether it is simply Deneuve's natural ice-queen demeanor being perfectly matched with her character. On the other hand, the credit might belong to legendary Spanish filmmaker Luis Bunuel — a bit of inspired casting followed up by strict direction.

But there's no arguing that in more than 60 films over the past 40 years, Deneuve has seldom come close to matching her startling turn in this 1967 French classic.

"Belle de Jour" stars Deneuve as Severine, who has recently married a well-to-do surgeon, Pierre (Jean Sorel) — and on the surface they appear to be a happily married couple. But Severine, as we learn from the opening sequence, frequently allows her mind to drift off into sexual daydreams, which involve bondage and humiliation.

Obviously troubled by her own inhibitions (and a secret from her past), Severine becomes rather excited at the prospect of freeing them when she discovers in a casual conversation that an acquaintance has quietly taken part-time work in a high-class, exclusive brothel.

Severine decides to approach Mme. Anais (Genevieve Page), who runs the operation, though she is, at first, quite nervous. Eventually, she does go to work for Mme. Anais and becomes one of the most popular prostitutes there, unbeknownst to her husband. Since she will work only only during the day, she is soon nicknamed "Belle de Jour," which means "Beauty of the Day."

Much of the bordello bed-hopping in "Belle de Jour" is portrayed for comic effect, and the film can be taken as a dark satire. But soon Severine will have a couple of run-ins there that will cause the "reality" of her married life to crash head-on with the "fantasy" life she has chosen — with tragic results.

Bunuel, who was 67 when he made "Belle de Jour" and was working with color for the first time, gives the film a gorgeous, lyrical sheen, which allows him to surprise the audience with the story's perverse underpinnings. In a similar way, he also uses Deneuve's "perfect" beauty and her aloof acting style to set up the audience for her unexpected behavior.

In addition, the film's shifts from reality to fantasy arrive without warning, making them initially difficult to separate and causing the latter to become even more shocking. (The fact that there is no musical background score also helps elevate the film's abstract sensibility.)

In truth, however, compared to graphic contemporary sex-and-violence standards, "Belle de Jour" is quite tame and may even seem rather old-fashioned and prudish. Yet, as with all films that legitimately achieve "classic" status, this one holds up very well as a significant, thoughtful work by a genuine artist.

The result is a film that may be less shocking than it was in 1967, but is no less disturbing or mesmerizing.

"Belle de Jour" is rated R for violence, rape, sex, veiled nudity and profanity.