By Louis Auchincloss

Houghton Mifflin. 274 pp. $20.95

THOSE of us who may have come to agree with F. Scott Fitzgerald's famous observation that "the rich are different from you and me" (and not simply because, as Hemingway allegedly replied, they have more money) will find little evidence to the contrary in Louis Auchincloss's new novel and 33rd book of fiction, The Lady of Situations. For better or worse (better for the requirements of social comedy, worse for the purposes of achieving something more resonant and profound), the novel's characters could hardly be less like you and me (or at any rate, me). Indeed, what's intriguing about Auchincloss is how, over so long and prolific a career, he has managed to sustain such a lively, anthropological interest in this endogamous tribe that believes stepping down in the world means joining the middle class, and which, despite Auchincloss's familiarity with his literary milieu, he still seems to regard as a rare breed of exotica, native only to Newport and the very best Park Avenue addresses.

By the time the novel begins, its heroine (or perhaps one should say, its main character) has already taken a fairly considerable dive down the social ladder. Due to the combined effects of the Depression and her father's misguided stock market theories, Natica Chauncey has been reduced to the (by the novel's standards) Dickensian fate of living in the gatehouse of what was once her family's mansion. Luckily, Natica possesses several compensatory talents: beauty, intelligence, and, most important, a great gift for apparently effortless socio-political manipulation. Quicker than you can say post-debutante, Natica has found her way back into the glittery world from which she was once so rudely ejected.

Not unpredictably, Natica marries up -- and up. The Lady of Situations is the sort of novel that makes one hesitate to disclose what happens to these marriages, but allows one to take a certain gossipy pleasure in relating that there are several. And by the book's end Natica has become a Superheroine -- and also partly, Auchincloss suggests, a Frankenstein -- of the Age of the Liberated Woman. (An age that many of us, perhaps less gifted than Natica, are still waiting to see begin.)

Initially Auchincloss seems to be offering us an elegantly written, less meretricious version of those genre bestsellers in which female versions of the Horatio Alger hero marshal brains and bod for rapid personal advancement. But one soon realizes that The Lady of Situations is after something more subtle, risky and even brave. Auchincloss is describing a society that, by forbidding women to fully assert themselves, forces them to resort to the sorts of manipulation and chicanery at which Natica so excels. More striking, and more unusual, he is depicting the frustrations of a woman surrounded by, and married to, men less complex and smart than she is. The book's sharpest scenes owe their edge to the uncanny accuracy with which Auchincloss has captured the patronizing tones in which men, particularly older, powerful men, talk to women whom they consider attractive and for their sex surprisingly intelligent. (The novel is dedicated to Auchincloss's first grandchild, a granddaughter, and the extra-literary question that runs through the reader's mind is: What will this young woman think of all this, 30 years from now?)

TO HIS credit, Auchincloss has attempted to create in Natica a multifaceted woman, neither saint nor devil, a rounded character instead of a two-dimensional pro- or anti-feminist placard. In an interesting, complicated reversal, Natica thinks more sharply than the men around her but seems to feel less deeply; she's almost blithely cavalier about the lives she ruins in her ascent towards a successful legal career, marriage and Super Momhood.

But the trouble with this craftsmanlike, immensely readable novel is that, like Natica's dim, well-meaning husbands, we never quite understand her. Though for several hundred pages we learn exactly what and how she thinks, she retains a maddening opacity. It's tempting to blame it on Auchincloss's literary territory -- the rich are different from us, etc. But one mark of the very best fiction is its ability to blur these distinctions, to bridge gaps not only of social class but of nationality and even time. What Chekhov and Stendhal and (regardless of what he said) the early F. Scott Fitzgerald make us feel -- and Auchincloss does not -- is that in some essential way the rich are exactly like us.

Francine Prose is the author of seven novels and a recent short story collection, "Women and Children First."