This work of fiction--fiction?--tells the story of a chic, intelligent and accomplished woman named Rachel Samstat, a writer of popular cookbooks, whose Achilles' heel is that her taste in men is absolutely abominable. Her first husband was "a low-grade lunatic who kept hamsters." Now, as "Heartburn" opens, she has just discovered that her second husband, a celebrated Washington newspaper columnist, is madly in love with another woman; Rachel, as it happens, is seven months pregnant.

What we have here, then, are the basic ingredients for yet another tale of pathos and angst among the fast-track folk whose names routinely appear in the grocery-store magazines and gossip columns--a tale replete with psychiatrists, country houses, clever recipes and all the other paraphernalia of upper-middle-class life. Fortunately, though, in fiction as in journalism, Nora Ephron's instinct is for satire rather than angst, so she wisely has Rachel tell her story in a tone of self-mockery; only in the closing pages does she lapse into something approximating self-pity, which is understandable but not especially appealing.

Indeed, until those final pages Rachel works overtime to avoid melodrama. She prefers the mundane metaphor of heartburn to the hyperbolic one of heartbreak, and she knows how to laugh at the excess of her emotions even as they thrash about inside her:

"Heartburn. That, it seemed to me as I lay in bed, was what I was suffering from. That summed up the whole mess: heartburn. Compound heartburn. Double-digit heartburn. Terminal heartburn. The tears poured from my eyes as I lit on the image, and the only thing that might have made it even more satisfyingly melodramatic and masochistic would have been to be lying in the bathtub; nothing like crying in the tub for real self-pity, nothing like the moment when every last bit of you is wet, and wiping the tears from your eyes only means making your face even wetter."

Heaven knows she has ample reason for turning on the waterworks. She is 38 years old, the mother of a 2-year-old son with another soon to arrive, and she has just nosed out the news that Mark Feldman, her husband and a man "capable of having sex with a venetian blind," is in the midst of a torrid affair with one Thelma Rice, "a fairly tall person with a neck as long as an arm and a nose as long as a thumb and you should see her legs, never mind her feet, which are sort of splayed." When she confronts him with this discovery, Mark, who had persuaded her to marry him notwithstanding all the qualms created by her first marriage, pledges that he will stop seeing Thelma but goes right on doing so:

". . . I believed in Mark. My marriage to him was as willful an act as I have ever committed; I married him against all the evidence. I married him believing that marriage doesn't work, that love dies, that passion fades, and in so doing I became the kind of romantic only a cynic is truly capable of being. I see all that now. At the time, though, I saw nothing of the sort. I honestly believed that Mark had learned his lesson. Unfortunately, the lesson he learned wasn't the one I had in mind: what he learned is that he could do anything, and in the end there was a chance I'd take him back."

In the end, though, she does not; she takes her toddler and her infant back to Manhattan and begins a new life. But before reaching this gratifying if unsurprising conclusion, "Heartburn" meanders along a rather formless course that permits Ephron to take on, and occasionally demolish, a number of inviting targets. She can be painfully observant about upper-middle-class behavior; at one point she complains that "the major concrete achievement of the women's movement in the 1970s was the Dutch treat," and at another that the 1960s produced "the first wave of competitive cooking." Writing about Washington, though, she tends to says things we have heard many times before:

"Actually, there is no possible way a seated dinner party in Washington can ever be wonderful. After only half an hour of drinks, you are seated, seated forever, trapped between two immensely powerful men who think it's your function as their dinner partner to draw them out. You draw them out. You ask them about the SALT talks. You ask them about the firearms lobby. You ask them about their constituencies. You ask them about the next election. Dinner ends and everyone goes home . . ."

This might be devastating were it not so familiar. And "Heartburn" might be something more than a witty entertainment were it not for two crippling flaws. The first is that the satirical tone Ephron sustains for most of the narrative suddenly changes, in the last pages, to a mixture of anger and self-pity. When her psychiatrist asks Rachel why she insists on turning "everything into a story," she gives us four punchily melodramatic mini-paragraphs that just about sap the book of all its wit:

"Because if I tell the story, I control the version.

"Because if I tell the story, I can make you laugh, and I would rather have you laugh at me than feel sorry for me.

"Because if I tell the story, it doesn't hurt as much.

"Because if I tell the story, I can get on with it."

But it's the second flaw that really matters: Ephron never manages to give us any reason to care about any of the people in her story. What "Heartburn" says, although that does not seem to have been in the original plan, is that underneath their mastery of the paraphernalia and buzz-words of the good life, these fast-trackers are utterly shallow. Even Rachel herself, who is funny and appealing, doesn't seem to understand that the real emptiness in her life is not Mark's infidelity but her own absorption with the shiniest material and psychological accoutrements of the Me Decade; Rachel is likable, but there is less to her than meets the eye.

Ephron is a gifted stylist and satirist, and though the steady barrage of one-liners quickly becomes exhausting, "Heartburn" is amusing reading. She has some perceptive, sophisticated observations to offer on marriage, betrayal, motherhood and other consequential subjects. The problem is that her subjects may be consequential, but her people are not. CAPTION: Picture, Nora Ephron; copyright (c) 1983, Thomas Victor