A Homespun Morality : FORTUNATE LIVES <i> By Robb Forman Dew</i> , <i> (William Morrow: $20; 285 pp.)</i>

Robb Forman Dew is one of our premier chroniclers of the everyday. In her two previous novels--the award-winning “Dale Loves Sophie to Death” and “The Time of Her Life”--she has shown a keen eye for the untidy domestic minutia that is the very sinew of American middle-class life, and a generous understanding of the heart that beats within it: that odd, elastic, irreplaceable organ we call the Family.

This investigation of the familiar seems, for Dew, an affirmative one. Out of the most mundane materials--a thrown-together lunch, a stain on the carpet, the stifled yawn of a child--she fashions loose, low-key narratives that celebrate the quieter virtues, like patient endurance and forgiveness. There is something pleasingly, even daringly, old-fashioned about these books; a kind of homespun morality. As her protagonists Dinah and Martin Howells came to decide (paraphrasing Mies van der Rohe) at the end of “Dale Loves Sophie,” “God hides in the details.”

The Howellses are back in Dew’s third novel, “Fortunate Lives.” Several years have passed. Dinah and Martin are still very much together, and have settled into a rather comfortable middle age in the Massachusetts college town of West Bradford. There Martin teaches, Dinah rears the children, and they are generally “as subject to terror, to passion, to pleasure as any people anywhere. It is only that in their circumstances they are fortunate.”

We come to take this last sentence with a grain of salt. It so happens that a terrible tragedy has befallen the Howellses: the death of their middle child, Toby, in a freak car accident. However, recounted in flashback six years later, the loss seems to cast only a soft, blurry shadow over their present actions. They have weathered it, Dew suggests in careful prose, as they have weathered other, less dramatic turns in their lives, and are now getting on with things. Or trying to. “There is,” thinks Martin, a practical man, “no use in grief.”

The book takes place during one uneventful summer as the Howellses, looking to the future, prepare to send their eldest son, David, off to college. David is fidgety and private, and this withholding throws off his mother’s--indeed, the entire family’s--equilibrium. “I have no idea, these days, what my children imagine,” Dinah muses in one of her many failed letters on David’s behalf to Harvard’s dean of freshmen.

This turbulent miscommunication between a mother and her increasingly independent son is the axis around which the novel revolves. As time goes on, David’s imminent departure and his relationship with Netta Breckenridge--a frazzled single mother new to town--give rise to a number of emotional strains that may or may not have to do with Toby’s death. (Readers of “Dale Loves Sophie” may recall that that book, too, swung on the hinge of Toby’s mortality.) Dew wisely chooses not to push the causality button very hard. Still, because there is very little in the way of actual plot here, one is aware--perhaps too aware--of the offstage, gravitational weight of Toby, constantly threatening to tilt the narrative balance and throw us into a familiar melodrama.

That he doesn’t, and that the novel remains absorbing reading throughout, is a tribute to Dew’s powers of observation, the fine, precise light she casts on the domestic scene. She has a gift for hitting minor notes, unexpected moments of psychological acuity. Most of these belong to Dinah, a sensitive, insecure woman with little else to do, apparently, than monitor each tremor of the family web.

On the other hand, her thoughtfulness and detachment make her a perfect vehicle for a writer’s insight--as when, in the midst of a family argument, she regards her husband of many years and wants to “say that he had been loved too well for all of his life and it had left him diminished.” Or later, when she understands how her habitual admonitions to her children regarding safety and risk are doomed to irrelevance, that even her worst fears will merely be carried around as “anecdotes in the lives of her children.”

Amid these fine moments, however, there are a number of awkward passages wherein one becomes aware of the limitations of the author’s style. Her tendency to begin chapters after their dramatic substance has occurred, and then circle back, becomes less effective with repetition. The cool, placid tone is almost faultlessly controlled, but there’s a drawback: Scenes that call for heightened action, such as Martin’s confrontations with the boy who unwittingly caused Toby’s death, tend to fall flat. And in a novel that relies upon deft shifts in character and mood, it’s surprising to find so many lapses into omniscient overexplanation, as when, to take just one example, Dinah is “nauseated with the visceral acknowledgment of the feeling of abandonment.”

Still, readers able to see past these defects and enter the Howells’ world unimpeded will find much to admire in “Fortunate Lives.” For all its uneventfulness, this is a novel that heightens our senses, awakens us to the fragility of even the most cozy and familiar lives.