By Amy Sohn

Simon & Schuster. 320 pp. $23

In an era that regards "Sex and the City" as a cultural benchmark, Amy Sohn has become not merely an author but a brand. From her beginnings as a sex columnist for the cheeky weekly the New York Press, she has extended her franchise through a novel ("Run Catch Kiss"), cable-television cartoon ("Avenue Amy"), screenplays ("Spin the Bottle" and "Pagans") and glossy magazines (the "Naked City" feature in New York). If it is appropriate that she wrote the coffee-table companion book to "Sex and the City," it is even more fitting that she was once the subject of a PBS documentary titled "Inventing Yourself."

Of the young female writers to follow in Candace Bushnell's lucrative wake, with their randy exploits and sailors' mouths, Sohn has had some of the more intriguing things to say. She was one sexual adventuress who paused long enough in the bodice-ripping to touch on issues such as Jewish identity and the aphrodisiac appeal of monogamy.

Her new novel, "My Old Man," plainly aspires to be more than a chick-lit confection. The protagonist, Rachel Block, is a rabbinical school dropout, still humiliated by her failure to bring solace to a terminally ill patient, no matter how many theological chestnuts she quoted from Abraham Joshua Heschel and Harold Kushner. The scene of her deathbed incompetence opens "My Old Man" in high style, promising us in Rachel a lovable screw-up wrestling with issues of faith and belief.

Unfortunately, when those pages end, so does most of Sohn's literary daring. For its remainder, "My Old Man" plays in predictable ways on a contrived plot. Sohn spins out two intertwined lines of narrative -- one about Rachel's infatuation with a virile but emotionally distant lover and the other about her father's affair with one of her friends. Some pungent jokes aside, Sohn renders these stories not with the mixture of empathy and detachment that, say, Mona Simpson has brought to similar material, but rather with the unprocessed, artless emotion of journal entries.

We feel Sohn's lack of wise distance most acutely in the portrait of Richard Block's liaison with Liz Kaminsky. It is plausible enough that a man like Richard, who is in his early fifties and has been laid off from his job, might seek the foolish solace of an extramarital affair -- except that Sohn the writer (like Rachel the character) conveys no sense that he is attractive or restless, or anything but dutifully faithful to a wife going through menopause. And then, completely unbelievably, she matches him up with Liz the libertine, all vibrators and thongs, who is half his age.

After plenty of venting at both Richard and Liz, Rachel comes to what passes for the culminating insight in this novel. Her words, which would sound perfectly adequate for a voice-over closing 30 minutes of "Sex and the City," simply cannot redeem 300 pages of fiction: "I wanted to hate him but I couldn't. He was intrusive, clueless and stagnated, self-hating, parasitic, and unemployed, and still I loved him. Maybe this was what family meant, that in the precise moments you felt most misunderstood and violated, you were angry not because of what your parents did but because you loved them in spite of it."

The complementary story line in "My Old Man" traces Rachel's pursuit of Hank Powell, an independent film director in his late fifties. (Think of someone like Hal Hartley or a slightly older Kevin Smith.) Powell is reeling from a bitter and costly divorce, and so although he's more than amenable to casting Rachel in some of his favorite sexual scenarios, he will not let her sleep over or spend time with his young daughter. The more he pushes her away, the more she desires him; the more he subjugates her, the hotter she gets. Does any of this sound familiar?

Both of the novel's May-December flings provide Sohn with ample occasion to rely on her familiar formula of soft-core porn and one-liners.

Those are the elements, after all, of her brand. To these she slathers on name-dropping (Mira Sorvino, Harvey Keitel, Willem Dafoe) and product-placement for various dresses, boots and lingerie.

Readers who want the Amy Sohn they already know and love will not be disappointed. Those of us, though, who sense in her at least the traces of a Colette or a Philip Roth, someone whose carnal appetites coexist with an artistic soul, cannot help but think that the early promise of "My Old Man" was just a tease.