A Yankee in Virginia : A COUNTRY OF STRANGERS <i> by Susan Richards Shreve (Simon & Schuster: $17.95</i> ; <i> 288 pp.) </i>

It’s 1942 on a Northern Virginia farm and two families, one black and one white, are on a uniquely American collision course heading for violence.

Moses Bellows is a seething Othello who changed his wife’s name from May to Miracle after she slept with John Spencer, the aristocratic white owner of Elm Grove Farm. When Spencer mysteriously disappears, Moses moves his wife, his disturbed brother, Guy, and his sister-in-law, Aida, from their back-yard cabins into the big house where they live in splendor until Spencer is declared legally dead and the farm is sold to Yankee-born Washington bureaucrat Charley Fletcher.

Fletcher is a man for our season: an idealistic, naive, well-meaning liberal who sees himself as “a reasonable man whose deep passions, even anger, were held in check . . . he always kept the matters of his mind and heart in slender trays with dividers like the drawers in which dentists keep their sterilized tools.” When his sexual impotence worsens after the World War II Army declares him 4-F, he seeks a “defense against the impotence of a failed soldier” by becoming a self-appointed soldier in the South’s race war, vowing that his family and the Bellowses, relegated once more to their back-yard cabins, shall become friends.

Like many such Yankees before and since, Fletcher confuses blacks with his inconsistencies; one moment insisting that they call him by his first name, then giving Moses an order, then barking: “Don’t call me sir!”

The astute Moses recognizes Fletcher’s masochism and labels him “a peaceable man interested in war,” but a harder tension to deal with is Fletcher’s immature wife, sunk in sexual fantasies of former lovers, who transfers her interest to the black foreman, letting him see her breasts while she nurses her baby and pursuing him to an isolated field ostensibly to help him bale hay.

Meanwhile, Miracle’s pregnant 13-year-old niece, Prudential (her mother was inspired by an insurance company sign), arrives from South Carolina to have her baby in Virginia and give it to Moses and Miracle, who are childless.

Open warfare immediately breaks out between the black girl and the Fletcher’s 13-year-old daughter Kate when Prudential perches in a tree and urinates on Kate’s head. Kate decks her and spits in her face, and Prudential responds by making a Kate doll and sticking it with pins, but an unexpected truce takes place when Prudential finds out that a white boy at Kate’s segregated school dragged her into the bushes and tried to make her perform oral sex. Prudential, who has been impregnated by her own father, is stunned. “I had no idea that kind of misfortune could happen to a white girl,” she marvels, and takes revenge for Kate by throwing Clorox in the white boy’s face.

Knowing that her ineffectual parents could never solve her problems so well, Kate comes to love Prudential, and a powerful sense of sisterhood springs up between the two strong-minded teen-agers.

Fletcher pursues his masochistic goals by wandering through Washington’s black slums where he is nearly knifed while trying to do good. Finally he is inspired to invite the Bellowses to move back into the big house with the whites and become one big happy family. Guy’s wife Aida takes him up on it, but the hate-filled Guy, who has had “a doorbell in his brain” ever since a white man made fun of him, grabs his shotgun and goes after her.

This novel is a blend of solid triumphs and disappointing, sometimes puzzling failures. Shreve, author of the well-received ‘Queen of Hearts,’ builds tension relentlessly, portraying interracial sexual attraction without falling into steamy “Mandingo” stereotypes or painting Moses as a casting-office Noble Savage. She goes so far in the other direction that he often seems, in his grim rectitude, more like Adam Bede than a Southern black, while the Virginia locale slips away from the American South and feels, more often than not, like the Egdon Heath of Thomas Hardy.

Part of the problem is Shreve’s wooden dialogue. Neither the blacks nor the Virginia whites sound authentic. A man who opens fire on a house full of people does not use the word “angry,” he says “mad.” A black woman in the rural South of the ‘40s would not say “You heard me perfectly clear” but “You heard me true.” As for the white Virginia cops, when the Fletchers call them to stop a black altercation, they reply: “We stay out of their business if it’s personal.” Real Virginia cops of the ‘40s would have said what I heard so often when I was growing up in the locale of this novel: “It don’t matter what they do to each other.” If the author simply has a tin ear it can’t be helped, but if she avoided realistic speech for the sake of political correctness I would venture to suggest that part of today’s highly touted “sensitivity” is letting people talk the way they talk.