Nathalie is a surprisingly unsexy movie about sex. It's even more surprising considering its gorgeous cast: Fanny Ardant, Emmanuelle Béart and Gérard Depardieu. To be fair, its subject is a woman's pursuit of desire in the midst of a long marriage, and director Anne Fontaine and her co-writer Jacques Fieschi succeed in fashioning a provocative script. But the characters' interactions become repetitive, and the film's momentum withers on the vine.

The plot suggests that, contrary to popular opinion, not all French women take their husbands' philandering lightly. After Catherine (Ardant) discovers her husband, Bernard (Depardieu), is cheating on her, she wanders into a local sex club, and hires Marlene (Béart), a strikingly beautiful prostitute, to entice him. Catherine names this fictional character Nathalie. In return, Marlene/Nathalie is to report all their interactions. Catherine, a successful gynecologist, continues to go through the motions of a normal life: She works, has dinner with her husband and grown son, maintains a cordial relationship with Bernard, but she becomes increasingly obsessed by her meetings with Marlene. Bernard seems to accept the absence of passion in their marriage ("Perhaps it is inevitable; everything ends eventually") and appears devoted to Catherine, but she is clearly thrown by this realization of loss. The film allows Catherine's motivations to be ambiguous: Is she simply manipulating Bernard for a sense of control or setting him up in a revenge fantasy? Is she searching for the erotic secrets that will reveal him to her so that they can be closer? Whatever the character's initial motivations, Catherine finds herself on a quest to revive her dormant sexuality, in the hope that this will re-ignite intimacy in her marriage and passion in her life.

The widescreen format takes advantage of the actresses' sumptuous beauty. Even when the suspense lags, there are Ardant's amazing cheekbones and lush, dark hair, and Béart's enormous, sultry eyes and sensual body. Fontaine avoids graphic sex scenes, opting instead for graphic verbal descriptions, delivered with decreasing eroticism by Béart in a world-weary monotone. Initially, the scenes of Catherine listening to the younger woman describe her sexual escapades with Bernard are effective. Ardant's poised yet expressive face registers her complex responses. By turns she's jealous, repelled, attracted, angry, grateful. It's a subtle performance, anchoring the film's suspense. What is Catherine thinking, and what will she do? But as the story progresses, there's more of the same, and one wishes for something to happen, either with Bernard or Marlene or both. Depardieu, in his few scenes, does a good job making Bernard comprehensible and even sympathetic. When Catherine asks if he ever sees hookers, he shakes his head, "I find them glacial." Certainly that would describe Marlene, who logically cuts her emotions off from her customers, including Catherine at first. But it freezes Béart's performance, which often reads like a kinky fashion shoot. And the surprise twist at the end is so predictable that it falls flat.

While Fontaine infuses the film with atmospheric color (a lot of red and black) and a moody soundtrack (including songs by Leonard Cohen and Natacha Atlas), she fails to sustain the erotic tension of the early scenes and the suggestive pairing of a proper but still alluring middle-aged woman and a younger, sleek professional of a different sort. One can only wonder what Buñuel might have done with this material.

-Wendy R. Weinstein