Upstairs at New York's tony 21 Club, the scene resembles the reception after a Hollywood power wedding. Isabella Rossellini, Joan Didion, and John Gregory Dunne mill around the reception line while Warren Beatty, imperially slim, quietly holds court on the staircase. Disney studio chairman Jeffrey Katzenberg, the party's host, jovially works the room, proud as a father of the bride. The champagne flows copiously, and the woman of the moment inspires appropriate awed whispers: ''Isn't she beau-u-utiful? Oh, she glows!'' The resplendent one is Andie MacDowell, the model-turned-actress who is now turning star; the disheveled giant at her side is Gérard Depardieu, the beefy Sun King of French cinema.
But they are not a couple in fact, only in cinematic fantasy. In Peter Weir's new movie, Green Card whose Dec. 1 celebrity screening is the occasion for this party the characters played by Depardieu and MacDowell enter a sham marriage so he can avoid deportation to France and she can get a posh Gotham apartment in a co-op whose board frowns on singles. Disney is looking to their unlikely romance to attract the same moviegoers who made the studio's Pretty Woman one of 1990's biggest hits.
Though their marriage is make-believe, the bash is charged with the same mix of giddy anticipation and firmly suppressed fear that energizes the most memorable weddings. Both actors have plenty to celebrate, but could be forgiven a few jitters as well. Depardieu is making his debut in American films. And after her superb turn as the romantically reawakened housewife in 1989's sex, lies, and videotape, MacDowell is hoping Green Card, Weir's follow-up to Dead Poets Society, will serve as her passport to the big time.
Swirling through the crowded room, she is stunning tonight, smiling expertly and fielding compliments like a seasoned pro. MacDowell's movie career got an awkward start in 1984 when her lines in Greystoke: The Legend of Tarzan, Lord of the Apes were overdubbed by Glenn Close (director Hugh Hudson decided MacDowell's Southern accent was too ripe for the character, a Baltimore belle). Now she betrays the merest hint of her origins in tiny Gaffney, S.C., as she indefatigably murmurs, ''Why, thank you'' in gracious broadcast English.
Over a lunch of Caesar salad and decaf cappucino in a restaurant near Central Park two weeks later, MacDowell, 32, is a bit tense. The crush of interviews and photo shoots to promote Green Card has left her a bit worn and more than a little nervous about how the picture will be received. What's worse, she's uneasy about her son Justin, 4, and daughter Rainey, 20 months, suffering from earaches in the upstate New York home she shares with husband Paul Qualley, a model. When I mention I've seen Green Card at a sneak preview for ordinary moviegoers (as distinguished from the rich and famous who were invited to the screening), her brow furrows and she presses for details. ''How did they react?'' she asks, stirring her decaf.