By Joyce Carol Oates

Dutton/William Abrahams

373 pp. $18.95

JOYCE CAROL OATES'S heart-rending new novel begins with a characteristically horrifying scene. It's the early spring of 1956 in Hammond, N.Y., a grimy upstate river town, and an elderly fisherman has just made a terrible discovery. As the dawn mist rises off the river, he suddenly realizes that the partly submerged object he'd mistaken for a heap of rags or an animal carcass is a human corpse, "floating in the water amid the river debris and froth with a look delicate as lace."

"White, or colored?" the proprietor of a nearby diner demands immediately -- as if it mattered. Yet as Iris Courtney, Oates's tormented young heroine, will learn, in Hammond in the mid-1950s, race matters a great deal: every bit as much, in fact, as in the Bronx or Chicago or Birmingham or Selma, though it may not be so obvious at first.

Of course, race is of paramount importance in Hammond's "Lowertown," where "the buildings and houses and even the trees become shabbier, {and} there is an increase of dark faces, an ebbing of white faces." It matters in Iris's sixth-grade classroom, where students are seated according to "a highly convoluted system of private classification," a system that depends, in part, on color. Later on, Iris realizes that "racial balance" is a major consideration on the basketball team of Hammond High, where her friend Jinx Fairchild, one of two black team members, may very well be the greatest player in the school's history.

At home, Iris is puzzled to hear her father, "Duke" Courtney, who considers himself to be an enlightened man, warn her: "These colored kids, you know . . . don't get too friendly with them. And don't ever be alone with them. The things a black man would like to do to a white girl . . . Christ, you wouldn't even want to think." Even the kindly Savage family, who befriend Iris during her college years, maintain invisible but sharp distinctions between themselves and their black help.

Fortunately, Iris Courtney is far too bright to buy into the mindless racism inherent in our society during her youth. But one night soon after she turns 14, a murderous street fighter named Little Red Garlock taunts her and Jinx Fairchild with obscene racial slurs, then attacks Jinx with a chunk of concrete. Battling for his life, Jinx accidentally kills Little Red (it's his body the fisherman spots in the river the next morning); and from that moment on, Iris and Jinx are linked by a powerful bond of secrecy, guilt and, ultimately, a kind of fateful love, which makes for as compelling a story about the tragedy of American racism as any I've read since David Bradley's The Chaneysville Incident.

Haunted by nightmares of the electric chair, Jinx finds relief only when he's playing basketball. Joyce Carol Oates writes wonderfully well about sports of all kinds, from boxing to automobile racing, and some of the best passages in the novel describe Jinx's games. "Iceman," he's called, though sometimes when he steps to the foul line at a critical moment he still sees the maniacal face of Little Red Garlock "grinning at him, showing his crazy teeth, and the hair lifting in snaky tufts in the moonlit water, and the eyes, the wide open dead eyes . . ."

Iris, in the meantime, has found a refuge in her omnivorous reading. Also she works long hours at various after-school jobs to help support herself and her mother, now abandoned by Duke Courtney and fast turning into an alcoholic. In some of the most affecting scenes in the novel, Iris tries to deepen her relationship with Jinx, meeting him in secret, giving him small presents. But besides the nearly insurmountable racial barriers of the times, "there's an intensity in Iris's behavior that makes him uncomfortable."

A SIMILAR intensity in Joyce Carol Oates's fiction over the past three decades has made some of her readers and critics uncomfortable. Her best novels are strongly reminiscent of Faulkner's, especially in their uncompromised vision of the violence her characters visit upon one another and themselves. Even her humor -- and she can be hilariously funny -- is mordantly ironical. And readers should be warned that in Because It is Bitter, and Because It is My Heart (the title comes from an appropriately grim poem by Stephen Crane) Oates spares us no detail in her graphic yet elegantly controlled descriptions of the fierce struggle to the death between Jinx and Little Red; the flaying alive of Jinx's street-wise older brother, Sugar Baby, by rival gangsters; the delirium tremens and death throes of Iris's once-beautiful mother; and finally, Iris's brutal personal experience with racial hatred in the heart of a dangerous city neighborhood on the night of President Kennedy's assassination.

"I must learn to forget," Iris observes in her battered old journal near the end of the story.

It's both a brave sentiment and the culminating irony of this stately, tragic novel. For how can Iris Courtney ever possibly forget what she and Jinx Fairchild have been through? The best she can hope for now, Oates suggests, is the security of an education, and a marriage based on convenience rather than love, in a world where the most talented young black men Iris grew up with regard the army and Vietnam as a preferable alternative to their hopeless lives at home. "How happy I am," Iris repeatedly confides to her journal. But we don't believe her for a single minute -- her insistence upon her happiness is just one more dreadful irony.

Because It is Bitter, and Because It is My Heart will probably dismay readers who supposed that the worst racial injustices in this country have been confined to the South and our large cities. It will undoubtedly sadden many others, for it is a terribly sad book indeed. But of Joyce Carol Oates's 20 novels to date, this one may endure the longest.

Wrought from an era of hatred and violence and despair, it is a splendid artistic achievement: the best and truest book so far by one of America's finest realistic novelists.

Howard Frank Mosher's latest novel, "A Stranger in the Kingdom," deals with a racial incident in northern Vermont in 1952.