BOOK REVIEW : Troubled Family Needs a Reality Check : BEFORE AND AFTER <i> By Rosellen Brown</i> ; Farrar Straus Giroux; $21; 354 pages

A fortunate family, the Reisers. Carolyn is a successful and devoted pediatrician in the bucolic New Hampshire town to which they have moved. They have added neat modernizing touches to their old farmhouse. Ben makes sculptures out of “found objects”; he is fulfilled, although he doesn’t make much money. On the other hand, he makes gourmet meals and is an eager if compulsive househusband. They have two bright teen-agers, even if Jacob seems a bit absent, and Judith, his younger sister, is moody.

Nice people, all in all, and a nice life. They pretty much fit in with their small-town neighbors, although a handyman friend is a mite quizzical about the imported beer and the new picture window, and the town police chief once hauled away, as litter, a welded collage of “objects” Ben had contributed to the town park. Still, they have won a place in the community, and differences of class and taste are, if not minor, ignored.

Until one evening, the police chief drives up and, after some awkward neighborly chitchat, tells them that a local girl has been found dead with a crushed skull. Jacob was the last person seen in her company, he says, and he’d like to talk to him. Jacob is not to be found, though. When Ben goes out to check the car after some aggressive stonewalling, he finds blood all over the mats in the trunk and embedded in the head of the jack. Impulsively, he burns the mats and disassembles and hides the jack.

It is a kinetic start to what at first seems to be a story of terrible things happening to nice people and--besides the mystery of what really happens--of the individual agonies, the cruel testing of family ties, and the moral dilemmas set off. It is darker than that, in fact. “Nice” is a lid over a family with gears that are set wrong and that strip under the load of tragedy.

Rosellen Brown’s novel is well-paced, and she sharply layers each strand of suspense. What did Jacob do, first of all, and when that pretty much becomes evident midway, how will the four of them respond to their knowledge and what will that response do to them as individuals and as a family? The disparate moral choices made by Ben, Carolyn, Jacob and Judith are the book’s true and distinctive climax. And throughout, of course, we try to discover who each of them is and what moves them.

The strength of “Before and After” lies in its tight narrative flow and in the questions it explores: male and female strengths, weaknesses and ways of reacting; the conflicting impulses to act in a crisis before knowing or to know before acting, and the relative duties owed to family solidarity, society and truth. Its weakness is the tidiness with which Brown sets her scene and plants her psychological clues, and the feverish and often coarse depiction of Ben’s and Carolyn’s thoughts and emotions.

The result, curiously, is not intensity but thinness of characterization, as if in their strident monologuing the adults, at least, had out-voiced their own individuality.

Jacob is impenetrably mute; only Judith emerges as a real presence. She is the book’s still center, and all of a sudden, exhilaratingly, its moral voice. We must tell the truth or destroy ourselves, she insists. The imperative will align Carolyn with her on one side, and Jacob and Ben on the other. It is a memorable portrait of that brief time in adolescence when moral choice may actually become character.

The story, whose details would be unfair to disclose, moves through the search for Jacob, who sends a series of puzzling and disturbing postcards, and who is found, arraigned and freed on bail. It takes us through the reactions of a community in which class differences as well as a general conviction of Jacob’s guilt serve to isolate the Reisers. It touches on two trials and ends with a subdued but illuminating postscript.

The townspeople and their reactions are set out routinely, not quite approaching cliche. The scrappy Greek-American lawyer who defends Jacob promises to develop some interesting complexity but never quite does. He comes to sudden, almost comically outraged life, though, when the family’s differences lead Ben and Carolyn into giving two vastly different testimonies to a grand jury.

Ben, who starts out as passively overbearing and disagreeable, sheds the passiveness and grows even less agreeable. His hyperactive impulse to act at all costs to protect Jacob--his father’s motto was “Honor thy children”--comes to seem like a denial of everything that nourishes life, including freedom; including even Jacob’s freedom. Jacob’s acquiescence to his father’s strategies masks a frozen and disturbing sensibility. Carolyn’s initial acquiescence is more human and endearing; as she puzzles her way out of it, she comes to seem increasingly vapid.

“Before and After” is often compelling and frequently provocative, but in her story of a dysfunctional family, Brown fails to give three of the four main characters much reality beyond their dysfunctioning.