Fissures Under the Crust : BLACK DOGS, <i> By Ian McEwan (Doubleday: $19.50; 149 pp.)</i>

The anticipatory chill begins with the title, “Black Dogs.” Fans of Ian McEwan’s fiction know better than to envision cuddly house pets. Hounds of the general size and ferocity of the Baskerville beasts would be more likely. In four previous novels and two short-story collections, the 44-year-old Briton has proven himself to be a master of menace, an excavator of the jagged fissures that lie just under civilization’s crust. McEwan’s menaces often take the form of actual dismemberment and sexual perversity. The civilization is all in his prose: an eminently British combination of lucid syntax and detached compassion.

“Black Dogs,” however, begins with disconcerting gentleness. A pleasantly tweedy narrator, who in the superficial details of gender, age, nationality, profession and number of children resembles McEwan, reminisces about his adolescent fascination with other people’s parents by way of introducing his main subject: a portrait of his in-laws. In previous novels, “The Child in Time” and “The Innocent,” McEwan evoked contemporary genres like “missing-child thriller” or “anti-hero spy novel” before bending them to his own purposes; in “Black Dogs,” the writing is simple and confessional, the apparent frankness disarming.

Described by their son-in-law, Bernard and June Tramaine are admirable, articulate and infuriating--a kind of Everyparent, elder variety. Their oddity lies in their decades-long marriage, a union at once loving and irreconcilable, fruitful and desolate. Bernard, who became a communist as a young man, is now an Establishment figure, a former Member of Parliament and Labour Party stalwart. He is a rationalist, a secular humanist, a man who collects and mounts insects with scientific precision and still believes in the perfectibility of systems that deliver social welfare.

June, when the novel opens in 1987, is bedridden in a suburban English nursing home, suffering from an obscure form of cancer. In the solitude imposed by uncongenial surroundings, she reads and writes, trades wildflower lore with her doctor and dispenses pointed advice to her children, all with the serene authority of her spiritual mentor, Lao tzu.

In 1946 she had been as eager as Bernard to join the Party, but her faith was shattered by a traumatic experience during their honeymoon tour of France. One effect of the trauma was that she discovered God, and in time it became apparent that not only her politics but her life with Bernard could not survive her religious conversion.

To an activist and intellectual like Bernard, June’s retreat into spirituality (amid the rustic comforts of a French farmhouse) is evidence of either massive self-indulgence or an elective lobotomy. To June, Bernard’s life of sound and fury has resulted in the predictable emptiness: The suffering still suffer. Meanwhile, his plummy elder-statesman manner drives her wild.

No one is less forgiving of another’s point of view than someone who hoped to change the world. But no one is more persistent, either. And so despite 35 years apart, their marriage survives--in a fashion. Instead of speaking to each other, they constantly lecture their family and anyone else who will listen on each other’s errors of temperament and philosophy.

And the menacing dogs of McEwan’s title? They’re there from the beginning, slavering at the edges of the narrative, pounding through June’s consciousness as she drops to sleep each night, the agents of her trauma, symbol of her satori--although, as McEwan’s narrator warns, she would disagree: “No, you clot. Not symbolic! . . . Literal, anecdotal, true. Don’t you know I was nearly killed!”

Unlike Henry James, who, abhorring banality, once described a neighbor’s pet, also a black dog, as “something dark, something canine,” McEwan finds the bald statement, the literal truth full enough of ambiguity.

Banality in fact fascinates McEwan, in particular the banality of evil, and part of the chill of his books comes from his ability to recount the most grisly events in cool and meticulously observed detail. Yet his is not the scientific detachment that collapses polarities, allowing good to become indistinguishable from evil. Rather he seems anxious to identify the cracked steps, the crucibles of experience that jolt individuals, for better or worse, out of their moral skins.

June’s black dogs are one such crucible--a half-starved, feral legacy from the Gestapo whose forces--only two years before the Tramaines’ honeymoon in the Languedoc--had terrorized these quiet villages.

“You wait until you come to make sense of your life,” June tells the narrator in their last interview. “You’ll either find you’re too old and lazy to make the attempt, or you’ll do what I’ve done, single out a certain event, find in something ordinary and explicable a means of expressing what might otherwise be lost to you--a conflict, a change of heart, a new understanding.” Part of McEwan’s fascination in “Black Dogs” is also reserved for people like Bernard who are not changed by circumstances. Even his beating at the hands of an angry Berlin mob is defanged by his protective coating of rationalism and self-esteem. In Berlin to celebrate the opening of the Wall, he springs to the defense of a red-flag-waving youth.

“It wasn’t his red flag, you know,” Bernard says the next day. “I don’t think they even saw it. You heard what they were shouting? Foreigners out!”

In the novel’s preface, McEwan’s narrator outlines the reasons for his obsession with his in-laws, calling the elder Tramaines “the extremities, the twin poles along whose slippery axis my own unbelief slithers and never comes to rest.” But his obsession has a more personal cause as well. Orphaned in childhood, he is acutely aware that all children are in a sense a reconciliation of opposites, a synthesis between two points of view that in his case remain unknown. “Nor will it do,” he warns, “to suggest that both . . . are correct. To believe everything, to make no choices, amounts to much the same thing, to my mind, as believing nothing at all.”

By the book’s end one thing is certain to rationalists and mystics alike: June’s dogs come between people. Forty years later they’re still causing arguments among neighbors in a French village. Was an earlier victim of the dogs--when their German masters were still on the scene--an informer, as some of the villagers suspected, or a pretty woman whose aloofness offended her male neighbors? The arguments, like the schism in a marriage, go way beyond a single incident or a pair of beasts, go beyond intellectual opposites to fundamental polarities including gender. And McEwan’s preoccupation with menace is revealed as part of a larger preoccupation with humanity.