Candace Bushnell doesn't write either of the two things people think she does: light fiction or modern-day versions of Edith Wharton's turn-of-the-20th-century novels of manners. The newspaper column on which the HBO series ''Sex and the City'' was based had sharper teeth and a flintier heart than that essentially romantic show; readers who grab Bushnell's books looking for hip, sexy froth tend to wind up complaining that they're too depressing. And though Bushnell herself encourages the Wharton comparison, the two writers share little more than an interest in ambivalent gold diggers and the cruelties of New York society's upper crust. Bushnell has neither Wharton's elegance of style nor her psychological acuity (not to mention her firm grasp of English grammar).
Too honest to be trash, too crude to be art, Bushnell's fiction is a peculiar hybrid that, in torturing itself over what it ought to be, exerts an unwholesome fascination. She has the good sense, for example, to place the morally challenged model Janey Wilcox, introduced in her 2000 story collection ''Four Blondes,'' at the center of her first novel, Trading Up. But Bushnell also wants her disdain for her protagonist clearly established up front. Janey opens the book in a silver Porsche Boxter convertible headed to a weekend resort area, thinking ''it was so passé to be stuck in traffic on the way out to the Hamptons, especially if you were a supermodel'' and pining for the seaplane taken by richer New Yorkers, before taking comfort in her ''pink Chanel sunglasses -- the must-have accessory of the summer.'' Then Bushnell explains: ''Janey was one of those people for whom the superficial comfortingly masks an inner void.'' Really? You think so?
In ''Four Blondes,'' Janey had begun to doubt the wisdom of her custom of hooking up with a different wealthy man each summer in order to savor the delights of the Hamptons free of charge -- financially, at least. ''Trading Up'' finds her much better situated, having signed a contract with Victoria's Secret that has ''her face plastered on billboards and featured in every magazine in America.'' She now rates an invitation to an old-money socialite's A-list Memorial Day weekend party, a marriage proposal from an up-and-coming media mogul, and prime seating in Manhattan's trendiest restaurant. By rights, she ought to be in heaven, but there's that little matter of an inner void, and no sooner does Janey snag the goodies she craves than she starts hankering for more.
Selfish, fickle, and occasionally outright deluded, Janey makes an unlikely heroine: Her chief claim on our sympathy is her indomitable will, though she can never quite settle on what she really wants. She's Scarlett O'Hara without a plantation or, more to the point, a civil war to test her mettle. ''Trading Up'' is full of bleak musings on ''arrogant rich men who traded pretty young girls like baseball cards'' and the pitfalls of being beautiful, but unlike Wharton's tragic characters, Janey isn't trapped by anything bigger than her own laziness, pretensions, and greed. If she sells her soul, it's for designer clothes. And does Bushnell fully exploit the opportunity for social satire here? That depends on whether lines like ''another rule of New York: One man's misery is another man's triumph'' strike you as witty insight and how much you thrill to learn that ''Nice to see you again'' is ''the ultimate New York dismissal.'' For all its racy trappings, ''Trading Up'' delivers a message that's surprisingly prim, whispering that rich, gorgeous celebrities have crummier marriages, cattier friends, and more lackluster sex lives than the rubes who follow their exploits on the gossip pages.