Altitude and Attitude : DEATH IN THE ANDES,<i> By Mario Vargas Llosa</i> .<i> Translated by Edith Grossman (Farrar, Straus & Giroux: $24; 336 pp.)</i>

In the Andean regions of South America, travel is by altitudes; new worlds, climates and cultures are discovered not by going north, south, east or west but by going up or down. Those who live at the temperate altitudes (sea level to 4,000 or 5,000 feet) experience physical and psychological malaise when visiting the much higher cities of La Paz and Cuzco, a malady locally called soroche.

In a much broader sense, soroche is the theme and illness in a new novel by the urbane, prodigiously gifted Peruvian novelist Mario Vargas Llosa. He is a lowlander whose life has been spent in Lima, Piura and Arequipa as well as in Europe and Mexico. “Death in the Andes” is his “Heart of Darkness,” reached not by traveling up a river in Africa but by climbing 12,000 feet into the central Andes.

The barren upland is home to the impoverished Indian descendants of the peoples whom the Incas ruled and, latterly, to the Sendero Luminoso (Shining Path), a deviant Maoist cult that has posed a violent guerrilla threat to the country’s stability. The fear inspired by Sendero in Peru’s cities is something more than that of violent revolution; it carries the suggestion of the upland--silent, ignored, mysterious--descending like extra-planetary raiders upon the known world.

In “The Real Life of Alejandro Mayta,” one of Vargas Llosa’s strongest books, the author wrote of a movement somewhat resembling the Sendero. It was a psychological and political portrait of a Lima activist who turns his back on his fellow Marxists to work with a charismatic leader among the Indians in the mountains. “Death in the Andes,” less successful and more awkward but in some ways more haunting, attempts to portray the Sendero from the point of view of those Indians and those mountains.

It tells several different stories, related or in counterpoint to one another. It uses a variety of tones--realistic and dreamlike, with odd simultaneity of past and present, of incident and hallucination--often woven into the same paragraph. It confuses, it gets out of hand, and it is meant to. Vargas Llosa is evoking a ghost-ridden world which baffles those who come to it from outside, and into which those who live there--whether natives or Sendero activists--disappear and become part ghost themselves.

“Death” centers on two likable and entirely human characters, a corporal and private--both lowlanders--in the Guardia Civil assigned to guard a highway construction project in the village of Naccos in the Central Andes. Two hundred Indian laborers work there; docile--except when inflamed by drink--and elliptical or entirely unresponsive to the efforts of Cpl. Lituma and Pvt. Carreno to investigate the disappearance of three fellow workers.

This is the heart of Sendero territory; Lituma and Carreno know themselves to be pitifully vulnerable to a raid that could take place at any moment. They suspect that the three missing men have been killed or abducted by the terrorists or terrucos, but have no way of knowing whether the workers--serruchos or sierra people--are spying for them. The flamboyant bar owner, Dionisio, and his fortune-telling wife, Adriana, seem to wield authority. Their own sympathies and connections are a mystery; they know a great deal and speak in hints and contradictions.

Vargas Llosa interjects two scenes in which the guerrillas appear, though not in the vicinity of Naccos. They stop a bus, pull out two young French tourists headed for Cuzco and stone them to death. They raid a reforestation project, capture a valiant and distinguished woman ecologist on an inspection visit and execute her.

The author conveys their chilling robotry; otherwise, he writes these scenes in a desultory, contrived manner. In “Death” his novelist’s interest is not really in the guerrillas themselves. It is in the upland: its Indians, the ghosts and legends that rule it and its ability to turn everyone who passes through, including the Sendero, into one more episode in a terrifying millennial history.

By day, Lituma and Carreno ask questions with no real hope of answers. At night, in their shack, they ward off their hopelessness and expectation of imminent death with the most human of lowland civilities: a story. In particular, a sexy story. In particular, the account by the youthful, naive Carreno of his one great love affair.

He served as bodyguard to a gangster--he got the job through his amiably corrupt godfather, a Guardia commander--fell in love with Mecha, the gangster’s mistress, killed his employer for abusing her and fled with her through Peru, stopping at hotels and making blissful love along the way. The story takes a series of picaresque twists; furthermore, it is more than a story.

Lituma keeps interrupting for details and comments. The two are weaving a fabric of civilization, and Vargas Llosa uses an odd weaving device. The story of Mecha, though told by Carreno as the past, is written in the present: Lituma’s interruptions take place in the same time frame as Carreno’s and Mecha’s comically erotic dialogues. It is as if Lituma were being invited in from the cold, ghost-haunted night outside.

The Lituma-Carreno story is rough and not particularly subtle or original; at times it seems close to puerile. But it provides a wonderfully fleshly contrast to the ghost-battling that the two policemen engage in by day.

They gather stories and stories that replace stories. The account of the three missing men are three ghostly vignettes of the upland, blending realism and fantasy. There is Pedro, the mute shepherd, who lovingly tended a herd of vicunas in caves far up the mountains. A Sendero unit machine-gunned them as part of its mission of destruction; they half-apologized to Pedro, who was heartbroken and subsequently fled to Naccos to work for Lituma.

There is the story of Casimiro, who escaped from the village where he was mayor when Sendero raiders arrived and persuaded the inhabitants to denounce and execute the leading citizens. There is the albino, who traveled the Central Andes as a peddler, seducing a succession of village women, one of whom later joined the guerrillas.

All three could have been victims of Sendero reprisals. But this notion gradually gives way to stories of landslides set off by angry deities, of monsters who suck the fat out of people, of mountain spirits who cause disasters. Lituma and Carreno hear accounts of human sacrifices practiced for centuries to prevent such things.

It seems clear that the three missing men were hurled down a mine shaft. Who hurled them? A crowd of villagers is described as lovingly conducting each of the three to the pithead, and praising and comforting them in advance of a propitiatory sacrifice. It is not clear who is describing this or why. Lituma, recovering from shock after nearly being caught in a landslide, seems to be hearing the story, but conceivably he could be hallucinating it.

Vargas Llosa has not drawn clear lines among events, stories, lies and the hysterical fantasies of two spooked policemen from the lowlands; or between guerrilla violence and that of a much older tradition.

But the theme of “Death” is powerful and suggestive. It is not that the Andes harbor Sendero guerrillas, but that they harbor 1,000 years of bloody subjection, along with the propitiatory rites that a powerless people devise to give the illusion that fate, if it can’t be avoided, can at least be negotiated with.