WHO KILLED PALOMINO MOLERO? by Mario Vargas Llosa; translated by Alfred MacAdam (Farrar, Straus & Giroux: $14.95; 134 pp.)

The classical English thriller concerns an aberrant action that shatters social order until the detective, an eccentric outsider or topsider on the order of Poirot, Wimsey or Campion, repairs the breach by solving the crime.

American thrillers--newer English school of Le Carre and his colleagues--have gone further and further in making society itself the mystery; the perpetrator, even. It is the hard-boiled or freeze-dried maverick who patches things up, though they won’t stay patched. Order is not restored; at most, there is a pause for breathing before the Establishment scoundrel will be at it again; and your tough paladin will be out on another job.

“Who Killed Palomino Molero?” may, at first, seem a departure from Mario Vargas Llosa’s big books on Latin America’s lethal social vortices. It is a little book, and it is a detective story. Yet it’s not mainly that. Mainly, it carries the American and the neo-English traditions to a savage extreme.

Its two detectives quickly discover the man responsible for the torture and brutal murder of a young airman near the Peruvian air base at Talara. The reader is perfectly aware of the perpetrator’s identity almost from the start. The mystery is not there, but in the social context. It’s not important or surprising to learn that the commander of the base had his subordinate killed for making love to his daughter and trying to marry wed. ?What is important is the morass in which the answer lodges.

In a community without social structure, the different powers--military, economic, political--fight or compromise from the individual corners, usually surreptitiously but with an occasional public flare-up. Society is simply the trackless no-mans-land between the contenders.

It is into this no-mans-land that Lt. Silva of the National Police and his sidekick, Lituma, find themselves launched when the horribly mutilated corpse of a young man is found impaled in a carob tree near the Talara Air Force base. Silva, bitter but honest, and Lituma, credulous but observant, are entrusted with the theoretical duty of finding the murderer and bringing him to justice.

The brief action takes place in the sunbaked torpor of a small seaside town near the base. In the foreground are the very modest lives and concerns of a few of the characters, which Vargas Llosa sets out in a vivid and expert shorthand.

There is Lituma, the sparky one in his circle of young men who hang about, not doing very much, and who live for their evenings at the local bar and brothel. “The Unstoppables,” they call themselves, in a grandiloquence traceable equally to small towns and worldwide television.

There is Lt. Silva, who hasn’t much to live for except his job and his obsession with the well-fleshed-and-aged endowments of Adriana, proprietor of the local restaurant. There is her husband, Matias, a gnarled fisherman whose frequent absences kindle Silva’s fantasies though not, unfortunately for him, Adrian’s passion.

It is a slow, poor and laconic existence; it is one part of the Third World. The air base is another part of that world; removed, arrogant and privileged by the money and arbitrary power that go to the armed forces in so much of Latin America.

The townspeople think of the base, or at least of its officers, as another kind of American; their special enclaved life could be that of the American engineers at the oil refinery. Vargas Llosa’s irony is agile and inspired.

Silva and Lituma represent the unprivileged civil authority of the National Police: Badly paid, demoralized and, by comparison with the military, an underclass. When they follow the trail of the dead airman to the base and its strutting and deadly commander, Col. Mindreau, they carry only the frailest thread of authority along with whatever individual bravery and persistence they can manage. They are two pygmies armed with spears against a pride of lions. But the lions are sick.

After an investigation marked by curt rebuffs, threats and a kind of dreamlike unreality, Silva and Lituma discover the colonel’s vulnerability. It is his anorexic, self-willed and half-mad daughter, a kind of starveling Lolita. She tips them off to the details of her lover’s brutal abduction.

But there is more to it. Silva’s hazily indirect questioning leads to a swamp. In their cut-off world, the colonel and his daughter had been living out a dark mixture of incestuous passion and the crazed machismo of power.

The crime is solved, but nothing else is. The two detectives have done their work, and punishment comes in a reasonably foreseeable fashion. But it is punishment only; not justice. The solution has no standing, no meaning. Nobody believes it.

Everyone in town knows far better than to accept Silva’s and Lituma’s account of a drama of twisted passion and authority. There has to be more to it. Clearly, there have been obscure high-level maneuverings, related to politics or perhaps drugs. Clearly, orders were given for the elimination of Col. Mindreau and his daughter; and for a cover-story. If at the end, Lituma gets a transfer order to a remote mountain post, far from his cronies, and if Silva faces some equally disagreeable change, that only proves the point.

Vargas Llosa may have invented the authentic Third World detective story. Facts need containers to hold them. In the author’s Peru, there is nothing to hold the containers. There is no society; merely a system of private arrangements that, in a contemporary world of oil and foreign investments and military aid programs, have lost whatever traditional values they may once have had. There is nowhere to put the truth.