"Night Games," an erotic trifle about a Bel Air housewife freed from sexual repression by a stealthy houseguest, suggests that Roger Vadim may be nodding off into somewhat premature senility. Vadim's work has never seemed profound, and his glamorous pictorial style has often been imposed on dreadfully trashy stories, but "Night Games" is fueled by such a tepid grade of gentlemanly voyeurism that it's the first Vadim picture that might be justifiably dismissed as harmless and antiquated.

There's a certain lack of concentration right from the beginning. "Night Games" opens with a sequence of the heroine, played by Cindy Pickett, and her best friend, played by Joanna Cassidy, jogging along the beach at Santa Monica in the morning. Certain vistas leave one with the distinct impression that the sun also rises in the Pacific.

The sound recording is consistently out of kilter, betraying a sloppy dependence on post-recorded recitation. Moreover, the sexual skittishness of Pickett, a thin, diminutive, pug-nosed actress with a vague resemblance to Vadim's most famous ex, Jane Fonda, isn't remotely as interesting as the composed, voluptuous presence of Cassidy, a statuesque redhead whose proportions would have delighted Rubens. Mysteriously underexploited for the past decade, Cassidy projects a humorous, overripe sex appeal that tends to dwarf the heroine's problems along with her physique.

Pickett is about to celebrate her second wedding anniversary with husband Barry Primus, a wealthy publisher. Unsubtle little clues point to a certain jumpiness about sex. When the couple retire to the bed chamber after an anniversary party, it becomes apparent that a traumatic memory -- adolescent rape -- returns to panic her each time her solicitous husband hopes to consummate the union. Frustrated again, he departs for a business trip in Europe, leaving the wife to knock around the mansion with only the furnishings, her fantasies, a couple of prowlers, a lot of strange noises and a fancy-dress sex therapist to keep her company.

Vadim probably intended the presence of the heroine's phantom lover to remain ambiguous until the denouement, but the plot is so thread-bare that his identity and reality can always be taken for granted. This lack of mystery makes the lover's therapeutic style of erotic theatricality seem even more preposterous than it would if attributed to sheer fantasy.

to be precise, the mystery lover appears to the heroine adorned in make and billowing capes.Her trauma is miraculously cured after two nights in the comforting embrace of this caped crusader. Evidently, a little masquerading was all she really needed to escape those bad old memories and contemplate an erotic future as enviable as her house and bank account. Obviously, the most appropriate title for this silly fable would be "Thank You, Masked Man."

Vadim retains his intutive appreciation of the erotic potential in movie imagery when concentrating on lush decor or compositions in the nude or semi-nude. What he desperately needs is a central character and a pretext diverting enough to rationalize a plunge into erotic dream states. From the beginning Pickett's character looks like a flimsy springboard for rapturous contemplation. The movie simply demonstrates how negligible her real life and fantasy life seem to be.

Even the promotional buildup for Cindy Pickett seems curiously wrongheaded, because she's likely to disappoint customers encouraged to think of her as a young actress as fresh and alluring as Bardot, Fonda and Deneuve when they were protegees of Vadim. She may be a decent actress (this role is too absurd to justify a decisive opinion), but it would be a miracle if she carried a picture on sheer sex appeal, as Bo Derek evidently has in "10."

Perhaps Vadim should be given a shot at Nancy Friday's "My Secret Garden," particularly in collaboration with a comedy writer. Given his eye and a sharp satire tone, that particular raw material might be refined into a peculiarly satisfying sex comedy.