Victims Under the Skin : THE INDIAN LAWYER<i> By James Welch (W.W. Norton: $18.95; 320 pp.) </i>

With “The Indian Lawyer,” novelist James Welch takes a giant step toward getting the wider audience he deserves. Like so many other serious novelists (Graham Greene, Robert Stone, James Crumley and Brian Moore, to name a good few), Welch has discovered that the thriller can be an excellent vehicle for a social novelist.

I’ve greatly admired Welch’s sad, lovely early books, “Winter in the Blood” and “The Death of Jim Loney,” neither of which were heavily plotted. They were lyrical and touching portraits of the world of the modern Indian, a world of broken promises, drunkenness and cracked hearts. Welch achieved his first breakthrough back in the early ‘70s when whacked-out white college kids were racing around trying to “commune with the Third World” (like transcendental, man!), but his artistry had nothing to do with faddish mysticism. Welch’s Indians might still go into the Smokehouse for a weekend of dancing and chanting but they don’t wind up transcending anything. Welch is too much of an artist to believe that the answer is a return to primitive roots. Indeed, he’s always been a tough, unsentimental writer; by that I mean he has been as tough on his own people as he has on the white society that has nearly decimated his culture.

“The Indian Lawyer” is still set in the American West, in the troubled, hidden world of the native American, but this time Welch has taken a different tack. His hero, the lawyer Sylvester Yellow Calf, seems to be one of the few Blackfeet Indians who has beaten the odds. Yellow Calf grew up on the Blackfeet Reservation in Browning, Mont. Smart, handsome and a great athlete, he led his high school team to victory in basketball. From there he ends up at Stanford Law, and as the book picks him up he’s a successful lawyer in Helena, Mont. Ahead lies an even better world--he’s being groomed by powerful politicos to run for Congress, and though he isn’t a shoo-in, everyone is confident that he’ll make it. Sylvester, it seems, is a golden boy, one in a thousand, untouched by his early poverty and despair.

A sportswriter in the novel, Ray Lundeen, is so taken with Yellow Calf’s athletic ability that he writes an open letter to him:

“ ‘Many of your teammates, Sylvester, will have their brief moment in the sun and will fall by the wayside, perhaps to a life of drink and degradation--so much a part of Indian experience--but you will, must carry the torch.’ ” He ends by calling Sylvester a “winner both on the court and off, in the past, present and future, in life--a winner for all minorities who fight the endless battle for respect and honor.”

Into this life of bright promises, however, comes Jack Harwood and his sexy, emotionally battered wife Patti Ann. A classic underachiever and minor psychopath, Harwood is the kind of man who has the brains to achieve anything but who is simply fascinated by a life of crime. He has a long arrest record, “five felonies, two armed robberies, one escape . . .” Worse for Harwood, he has been stabbed by an Indian inmate in the prison library, and he fears for his life.

As the novel opens, Harwood is up for parole, which he badly wants, but Yellow Calf and the parole board deny it to him. An Indian-hater to begin with, Harwood begins to fixate on Yellow Calf as the source of his troubles, and decides to use his sexually starved wife to ensnare Yellow Calf into a blackmailing scheme.

Patti Ann goes to see Yellow Calf on the pretext of having him look at a will involving some rare books, a pretext so lame that Yellow Calf is fairly certain she’s lying. Of course, he has no idea she’s Harwood’s wife, but he does realize that her cover story is bogus. Just the same, he’s deeply attracted to her, and doesn’t really want to ask her why she’s lying. This is Welch’s particularly brilliant insight into “minority psychology.” Though they have escaped the bonds of poverty, though they have won stardom on the athletic field and hard-earned success in their careers, their own deepest sexual feelings and passions may well be tied up with people who remind them of their own past. Sylvester is drawn to Patti as much by her pathetic situation, by the fact that she’s a victim, as he is by her obvious earthiness. Indeed, he nearly finds it impossible to distinguish one from the other. The question for Yellow Calf thus becomes elemental: Will he take care of himself and keep Patti out of his life, or will he be sucked into Harwood’s nasty little scheme and lose his main chance?

Since the book is structured like a thriller, it would be unfair to tell any more. But what makes the plot come to life are Welch’s exceptional characterizations. Every character, minor or major, is well drawn. Yellow Calf is a sympathetically rendered hero, a man who is macho, able and yet more than a little lost.

Harwood is not simply some pulp-thriller villain but himself a complex and interesting person. We can see why Patti would be drawn to him, and why she lets herself be manipulated by him. Furthermore, he serves as a doppelganger to Yellow Calf. Beneath the colors of their skins, Harwood and Yellow Calf are more alike than either of them knows. And Patti Ann is much more than just Harwood’s pawn. Indeed, she may be the most fully drawn and sympathetic character in the novel, a woman desperate for love, capable of betrayal, and yet oddly noble as well.

“The Indian Lawyer,” like all of Welch’s books, is subtle. Welch’s prose is deceptively plain-spoken; he’s no Robert Stone. His sentences don’t thrill us with their apocalyptic urgency. He doesn’t howl at the moon, or fire burning arrows into the circled wagons. Rather he moves quietly along, slowly, confidently building his fully realized world, tightening the noose.

His is an almost invisible style, and those of us who’ve grown addicted to the hyped-up styles of so many other thriller writers might find the voice a trifle flat. But don’t let that stop you from reading “The Indian Lawyer,” for it’s a book that gets stronger and reverberates more deeply as it moves toward its inevitable climax. Welch is an artist, daring more each time out, and “The Indian Lawyer” is a brilliant and haunting book.