RAMPLING'S PERFORMANCE IS OVER THE MOON.

Byline: Bob Strauss Film Critic

Charlotte Rampling, the very continental English actress known throughout the 1970s and '80s for the verve and conviction she brought to some of the most outrageous film roles ever imagined, does perhaps her best work ever in the low-key, very mature psychological study ``Under the Sand.''

The better news is that, in its way, this urbane and understated French drama is every bit as bizarre as ``The Night Porter,'' ``The Damned,'' ``Zardoz'' or ``Max My Love.'' But it marks a deeper interweaving of emotional honesty and aberrant behavior on Rampling's part; with this one, she finally makes the transition from an interestingly provocative actress to a great one.

``Sand'' is also a big step toward artistic adulthood for writer-director Francois Ozon, the reigning Gallic enfant terrible responsible for such showy assaults on propriety as ``Sitcom'' and ``Water Drops on Burning Rocks.'' Coolly but with subtle empathy, he details the respectful, if passion-bled, affection of a long, childless marriage and the failure to cope with such lukewarm comfort's disruption. At the age of 33, Ozon has made a film with insights and compassion one might more reasonably expect from a director twice his age - and only an unusually talented and sensitive one of that vintage.

During the last of many summer holidays at their country cottage, Rampling's Marie and Bruno Cremer's Jean Drillon go to a nearby beach. She falls asleep on the sand while he heads for a dip in the ocean. When Marie awakens, Jean is gone.

Cut to Paris, something like half a year later. Marie sparkles at a friend's small dinner party; Vincent (Jacques Nolot), a charming, single publisher about her age, is clearly smitten. Their mutual friends, however, are politely disconcerted whenever Marie speaks of her husband in the present tense. Not quite sure what to think - since he's surely been briefed by their matchmaking hostess that no trace of Jean has been found since that summer afternoon - Vincent steals a hungry kiss after escorting Marie home.

Shocked but a little thrilled, Marie beats a retreat to her handsome apartment - and to Jean. Or is it his ghost (he seems the soul of caring, sometimes even when she's not conscious)? Or, maybe, the figment of her denial, a spirit-and-flesh bulwark against acknowledging her grief? One thing's for sure; as far as anybody else is concerned, Jean has either died or run far, far away. But that very uncertainty about his fate is all Marie wants to cling to, rationally and otherwise.

However, the confused but persistent Vincent awakens the highly sensual woman in Marie (in one dreamy sequence, destined to become a cinema classic, she drifts into ecstasy as two sets of male hands caress her through her sensibly chic dress). This, in turn, tests her carefully constructed mental defenses to their limit.

OK, so maybe imagining a missing husband is still around doesn't register quite as high on the lunacy meter as playing sex games with a chimpanzee or your concentration camp commandant. But the way Rampling integrates Marie's delusion with the ongoing details of her life and love has a perversely poignant charge uniquely its own. More important, it's not the least bit ludicrous ... and Rampling, more radiant in her maturity than she has ever been on screen, relishes the opportunity to display her courage and imagination with, for a change, all the gravity that they deserve.

``UNDER THE SAND''

(Not rated: sex, nudity, language)

The stars: Charlotte Rampling, Bruno Cremer, Jacques Nolot.

Behind the scenes: Directed by Francois Ozon. Written by Ozon, Emmanuele Bernheim, Marina de Van and Marcia Romano. Produced by Olivier Delbosc and Marc Missonnier. Released by Winstar Cinema.

Running time: One hour, 35 minutes.

Playing: Westside Pavilion, West L.A.; Playhouse 7, Pasadena

Our rating: Three and one half stars