"All the Pretty Horses," the first volume of Cormac McCarthy's Border Trilogy and the work that transformed him in 1992 from an obscure cult writer into a National Book Award-winning, best-selling writer, also caused many of his old loyalists to desert the cult. The apostates, who included critics as distinguished as Denis Donoghue, were suspicious of the likability of the protagonist, John Grady, and felt that Mr. McCarthy's first non-necrophilic love story was a lapse into sentimentality. They were wrong, however, for the original dark chaos of Mr. McCarthy's vision is clearly present beneath the surface of "All the Pretty Horses." In the second volume, "The Crossing," that vision is right up front. Whatever gets said about this book, nobody will be able to mix it up with "Huckleberry Finn."

There is no plot continuity between "The Crossing" and its predecessor; no characters from the first volume reappear. Instead, the new novel is a variation on the tropes of the first: American youths traveling in and out of Mexico, trying as best they can to work out self-respecting accommodations with animals and with other human beings. As before, there are many encounters with Mexicans who speak in inscrutable parables and who prefer their own language to the extent that one is moved to wonder whether Mr. McCarthy's third installment will be written entirely in Spanish.

At the beginning, it seems that "The Crossing" will do for wolves what the first volume did for horses. Billy Parham, the 16-year-old son of a New Mexican ranch hand, sets out to trap a she-wolf that has migrated from Mexico and is killing stock. Mr. McCarthy develops the mystique of the wolf in much the same way that he handled the mystique of the horse in "All the Pretty Horses." Billy, seeking entry to these secrets, has an interview with an old Spanish-speaking trapper, who sets the issue in terms that will be familiar to Mr. McCarthy's old cult readers:

"The old man went on to say that the hunter was a different thing than men supposed. He said that men believe the blood of the slain to be of no consequence but that the wolf knows better. He said that the wolf is a being of great order and that it knows what men do not: that there is no order in the world save that which death has put there. Finally he said that if men drink the blood of God yet they do not understand the seriousness of what they do. He said that men wish to be serious but they do not understand how to be so. Between their acts and their ceremonies lies the world and in this world the storms blow and the trees twist in the wind and all the animals that God has made go to and fro yet this world men do not see. They see the acts of their own hands or see that which they name and call out to one another but the world between is invisible to them."

Then the old man goes on to say that what Billy must do is "find that place where the acts of God and those of man are of a piece. Where they cannot be distinguished." For the rest of the novel, this place becomes the object of his pilgrimage.

Billy catches the wolf alive, contrives to muzzle her, and on impulse decides to take her back to the Mexican mountains where she can safely be set free. But they are intercepted by corrupt Mexican officials, who steal the wolf and use her for entertainment and gambling in a dog pit. Billy's struggles to rescue the wolf drive him to truly moving heights of heroism, but these scenes of high drama come to no good end, and the outcome finally divests them even of their tragedy. The wolf episode is a spectacular set piece, and it may be that the essence of the story is all told here, but two-thirds of the novel are yet to come.

"Doomed enterprises divide lives forever into the then and the now," Mr. McCarthy writes, but Billy has many more dark fatalities in store for him. Returning from his burial of the murdered wolf and from a starved and solitary wandering through the Mexican hills, he recognizes his father's horse in a Mexican border town. When he reaches home, he finds his parents have been murdered in their bed, most likely by Indians whom Billy and his little brother, Boyd, had ill-advisedly led to their house for a handout. With Boyd, who's not quite 15, Billy returns to Mexico, seeking to recover the stolen horses and perhaps to win some unspecified revenge.

On this quest for a kind of justice, the boys meet with success or failure, respect or mistreatment, more or less at random. The vagaries of jurisdiction around the border give Mr. McCarthy a sheaf of useful metaphors for his idea that men seldom honor one another's covenants. Billy's American title papers to the horses are near worthless in Mexico; a "factura" written to protect them is good only to the boundary of the ranch. The frequent incursions into Spanish also serve this purpose, for the names that things are given affects not what they are, but how the characters can know them.

Slowly the boys' personal cause is subsumed in other causes. They never find the murderous Indians. In a scuffle over some of the stolen horses, a Mexican official is accidentally killed, and while in flight Boyd is wounded by a rifle shot. Because the dead official was known to be the betrayer of a revolutionary martyr called Socorra Rivera, Boyd is instantly transformed into a popular hero. When he recovers, he runs away with a girl the two boys had rescued from a rape. Unable to trace the horses, Billy returns stateside empty-handed for a second time.

But of course he must go back to Mexico, for there is nothing for him in the States, no family, no home, not even a place in the Army entering World War II (because of a disqualifying heart murmur). Boyd's path has now been mapped in Mexican folk songs, and the path leads to a grave, for this is a world in which "death was the condition of existence and life but an emanation thereof." There, and only there, the acts of God and man are unified.

Such a skeletal summary of the plot gives a false impression of this novel. As always, the richness of Mr. McCarthy's prose makes not only the work of most other writers but the world itself pale. Despite a degree of redundancy with the previous volume, "The Crossing" is still completely absorbing.

At least half its fascination comes from the anecdotes and parables and scraps of history that Billy hears from the numerous other pilgrims he meets along the way. There are many brilliant set pieces of this kind (including one that recalls the Book of Job, another that rivals the blinding of Gloucester in "King Lear"), and most have some bearing on the contradiction between Mr. McCarthy's bleakly anarchic view of the world itself and Billy's apparently fundamental decency within it.

Perhaps this paradox cannot be reconciled; it may be that Mr. McCarthy has no wish to reconcile it. Certainly his idea of the nature of things is more grim and violent than his new popular readership will find easy to digest. But along with being a great prose master, he is also a writer of real philosophical depth who has seriously interested himself in the problem of how ethics can be derived in a world whose essence does not in the least support moral behavior.

The answer is not fully given here, but seems to involve a theory that "what the dead have quit is itself no world but is also only the picture of the world in men's hearts . . . that the world cannot be quit for it is eternal in whatever form as are all things within it." In these terms, absolute truth remains unknowable, while the truths of the heart are valid (like facturas) for those willing to recognize them. Thus the Boyd of Billy's love and grief is no more and no less valid than the revolutionary Boyd of the Mexican corrida, because (as another of Mr. McCarthy's soothsayers has it) "rightly heard all the tales are one."

Mr. Bell is writer-in-residence at Goucher College. His most recent novel is "Save Me, Joe Louis."

Title: "The Crossing"

Author: Cormac McCarthy

Publisher: Knopf

Length, price: 421 pages, $23