JOHN EDGAR WIDEMAN is a novelist who came to literary prominence last year when his sixth book, Sent for You Yesterday, was enthusiastically reviewed and subsequently honored with the PEN/Faulkner Award. Now he has turned his hand to nonfiction, with powerful and disturbing results. Brothers and Keepers is a book guaranteed to shock and sadden, for it is the story of a gifted and intelligent man whose thoughtless and unwittingly self- destructive behavior led him ultimately to a state penitentiary. It is also a depiction of the inexorably widening chasm that divides middle-class black Americans from the black underclass, a chasm that has terrible effects both for specific individuals and for the larger society.

The imprisoned man is Robert Wideman. He is now in his mid-thirties and is 10 years younger than his brother, the author. Both grew up in Homewood, the black ghetto in Pittsburgh that is often the setting of Wideman's fiction, but biographical similarities end just about there. John Edgar Wideman is a graduate of the University of Pennsylvania who now teaches at the University of Wyoming, lives in Laramie with his wife, who is white, and their three children, and enjoys the attentions of the literary crowd. Robby Wideman, by contrast, drifted out of high school into a street life of drug-dealing and robbery that climaxed with his involvement in a fatal encounter; he is now serving a life sentence without parole at Western State Penitentiary in Pennsylvania, his only hope for freedom lying in the slender possibility that someday his sentence may be commuted by a forgiving governor.

THIS BOOK is the elder Wideman's effort to understand what happened, to confess and examine his own sense of guilt about his brother's fate (and his own), perhaps also to make a case for his brother's eventual release. "Even as I manufactured fiction from the events of my brother's life," he writes, "from the history of the family that had nurtured us both, I knew something of a different order remained to be extricated. The fiction writer was also a man with a real brother behind real bars. I continued to feel caged by my bewilderment, by my inability to see clearly, accurately, not only the last visit with my brother, but the whole long skein of our lives together and apart. So this book. This attempt to break out, to knock down the walls."

There are two voices in Brothers and Keepers. The principal one is Wideman's own; though at times it expresses the anguish he feels, for the most part it is cool, analytical, judicious, skeptical. The other is Robby's, mostly as heard by his brother in visiting hours at the prison; it too is cool, but this is street cool, and the language is that of the street. It is a language that sounds utterly alien to most white Americans, that is rarely heard in the novels Americans write, and it speaks of a world the sit-coms never show. Here, for example, is Robby talking about "the life" that is the stuff of street dreams:

"Straight people don't understand. I mean, they think dudes is after the things straight people got. It ain't that at all. People in the life ain't looking for no home and grass in the yard. . . . We the show people. The glamour people. Come on the set with the finest car, the finest women, the finest vines. Hear people talking about you. Hear the bar get quiet when you walk in the door. Throw down a yard and tell everybody drink up. See. It's rep. It's glamour. That's what it's about. What else a dude gon do in this . . . world. You make something out of nothing."

It was this dream -- "that Superfly fantasy," Robby calls it -- that led him to deal dope (and of course to use it), to walk off legitimate jobs when the mood suited him, to participate in various small-time heists and scams. One of these took place in November, 1975, when with two pals Robby attempted to out-hustle another petty crook; the trouble was that the petty crook got killed, and after a few months of flight Robby and his pals got caught. John Edgar Wideman sees the whole gloomy story as virtually preordained:

"Robby's chance for a normal life was as illusory as most citizens' chances to be elected to office or run a corporation. If 'normal' implies a decent job, an opportunity to receive at least minimal pay-off for years of drudgery, delayed gratification, then for Robby and 75 percent of young black males growing up in the 1960s, 'normal' was the exception rather than the rule. Robby was smart enough to see there was no light at the end of the long tunnel of hard work (if and when you could get it) and respectability. He was stubborn, aggressive, and prickly enough not to allow anyone to bully him into the tunnel. He chose the bright lights winking right in front of his face, just beyond his fingertips. For him and most of his buddies, 'normal' was poverty, drugs, street crime, Vietnam, or prison."

No, it won't do to say: You made it out of the ghetto, so why should we excuse your brother's failure to do so? Wideman knows that the story is far too complicated to fit so simplistic a formula. The elder brother knows that moving out of the ghetto into the white world is a process that requires excruciating compromises, sacrifices and denials, that leaves the person who makes the journey truly at home in neither the world he has entered nor the world he has left. He knows further that, as he says in the above paragraph, for urban black males who came along a decade later than he did there was a whole new set of circumstances with which to contend, not least of these being that the civil-rights revolution had raised expectations that the realities of ghetto life only mocked and dashed.

Wideman is no apologist for the shady life to which his brother aspired or for the terrible, stupid act in which he participated; he merely wants us to understand -- and wants himself to understand as well -- what it is like out there in "the life" and what it can do to those who try to live it. He further wants us to understand what it is to be in prison, under the cold surveillance of the "keepers," in a world where "nothing can be taken for granted except the arbitrary exercise of absolute power." In the end, this is what Wideman says: To himself, that the life his brother has lived is inextricably part of his own; to the rest of us, that unless we are morally bankrupt we cannot close our eyes to this life or our own complicity in its unhappy course.