Balloon in the Wind : BLACK NOVEL (WITH ARGENTINES), <i> By Luisa Valenzuela Translated from the Spanish by Toby Talbot (Simon & Schuster: $20; 220 pp.)</i>

In New York City, an expatriate Argentine writer named Agustin Palant buys a pistol for protection. One evening he takes a walk on the wild side. Among the pimps and drug pushers lurking in doorways is a mysterious man who gives him a ticket to one of the theaters that honeycomb the slums. An actress in the play he sees invites Palant to her apartment. The script seems to call for seduction, but instead Palant shoots her in the head.

Why? The question, like the echo of the shot, reverberates in Palant’s mind and almost shakes it apart. This is a murder without a motive. Nothing in his life, he thinks, has led up to it. He takes refuge in the home of his sometime girlfriend, another Argentine writer named Roberta, who doesn’t completely believe his story but finds him, if even more preoccupied and distant, more interesting than before.

At first, Luisa Valenzuela (“The Lizard’s Tail,” “Open Door”) seems to be writing a standard psychological novel--and an acute example of the genre, at that--but soon things give her away. Her language, for instance. It’s as antic and unpredictable as a balloon bobbing in the wind. Also, Palant’s search for the truth about the murder, and Roberta’s search for the truth about Palant, go off on crazy tangents. This is no meditation on guilt, like Paul Theroux’s “Chicago Loop.” Nor is it an existentialist celebration of a “gratuitous act.” It’s something else.

Something theatrical. “I’ve completely lost myself,” Palant thinks, hiding in Roberta’s apartment with his beard shaved, trying out aliases (they settle on Magoo). “Reached the point of not knowing where life begins and theater ends, or even worse, where theater begins and life ends, where life begins to end with all this theater.”

For when Palant wearies of playing the fugitive (because nobody seems to be hunting him) and Roberta wearies of playing the gangster’s moll, they go out to find all New York in a state of continuous performance. Businessmen playing victims patronize a torture chamber where a spike-heeled friend of Roberta’s, playing a sadist, administers carefully calibrated doses of pain. A “sublime old man,” a ballet master of Nijinsky’s era, lies dying behind a transparent wall, viewed by party-goers on the other side. Even the homeless in parks and shelters seem to be acting out some half-conscious drama.

Like stage sets taken down and reassembled for the next act, New York keeps on shifting. Palant can’t find the warehouse theater he visited on the fatal night. The store where he bought the pistol may have metamorphosed into an antique shop run by a black man who becomes Roberta’s next lover. Palant even wonders if the murder itself wasn’t elaborately staged, if he wasn’t given the ticket and led to kill the actress--or believe that he was killing her--for the secret amusement of some rich and powerful spectator.

At this point, we discover that Valenzuela’s balloon, however colorful, however wildly gyrating, is tied by a long string to something as dark and heavy as an anvil. Palant and Roberta are not just expatriates. Like Valenzuela herself, who spent several years in New York, they are self-exiles, haunted by Argentina’s “dirty war” of the 1970s and early ‘80s.

Back home, they know, the rich and powerful could arrange murders to their liking. In the torture chambers of the military regime, pain had no limits. New York may be dangerous, but for Argentines its dangers seem somehow unserious, even desirable, “dangers you were looking for because that after all is what it’s all about.”

Palant experiences New York as theater in part because he got used to play-acting in Buenos Aires, ignoring friends’ “disappearances,” fearing to speak out. The key to the murder, Valenzuela suggests, isn’t a quirk in his individual psychology so much as his infection by the “dirty war” which, like the AIDS virus, can hide for a long time in the system before the delayed trigger clicks.

Yet “Black Novel” isn’t standard political fare, either. This is a witty, sexy, literary book by a highly sophisticated writer, one who likes to play with male and female stereotypes and themes of dominance and submission, love and creativity. Some readers will groan: “Not another novel about novelists writing (or suffering writer’s block) about events that may be real and may just be made up.” Those who will enjoy Valenzuela are those who can play along--and follow that bouncing balloon.