ALMOST TWO DECADES AGO, American and European readers first started hearing about a "boom" in Latin American literature. Novelists like Colombia's Gabriel Garc,ia M,arquez, Argentina's Julio Cort,azar, Peru's Mario Vargas Llosa, to name only a few, were turning out some of the most exciting writing around. Out of nowhere, it seemed, a new and vibrant literature had burst on the world scene.

Some time later, Garc,ia M,arquez, author of One Hundred Years of Solitude, said: "The famous Latin American 'literary boom' is a lie; what is real is the Cuban Revolution." He meant that Latin American writers had been producing major novels before the "boom" but no one paid much attention. It took Fidel Castro's revolution to focus attention on the region and, by extension, on its literature.

Today, Latin America is once again on the world's front pages and television screens. Teenage guerrillas outmaneuver squat, sunglassed colonels on the battlefields and beat them to the network feeds. In Washington, an alarmed State Department hops from hysteria to farce and back again. Perhaps it is time to rediscover what Latin American writers are saying about their societies. For despite their reputation for uninhibited literary experimentation, expansive imaginations, and lavish use of myth and fantasy, most Latin American writers base their work on the political and economic reality of their countries.

Avon Books has been in the vanguard of publishers making that reality accessible to an American audience, with 22 titles since 1970 and more on the way. The Celebration is a brilliant Brazilian example of the concerns common to many Latin American writers, and of the dazzling literary skills they often bring to their work.

In this book, Ivan Angelo, a journalist turned novelist by censorship, paints an unsparing picture of the regime installed in Brazil by a military coup in 1964. It was the first in a series of right-wing coups which, by 1976, had turned the most advanced societies of South America into military dictatorships based on conservative economics and political terror, with all the by-now familiar trappings of censorship, political prisoners, quasi-official death squads, and routine use of torture. In short, the kind of regime Jeane Kirkpatrick, our U.N. ambassador, is happy to tolerate because it is only authoritarian.

The book opens with a riot at the railroad station in Belo Horizonte, a prosperous city in southern Brazil. Several hundred desperate, impoverished refugees from the drought- stricken northeast break through police lines and escape into the city. The police open fire, killing and wounding several. One of the dead is a young newspaper reporter named Samuel. There is evidence he helped the refugees break out of the station. Samuel, we learn later, had been invited to a birthday party for a bisexual artist that night--the celebration of the title: "You're gonna like this crowd, Samuel, lots of artists, writers, gorgeous women, queers, left- wingers, you name it."

By then, we've already met much of this crowd--mainly self-centered, insecure sophisticates--in chapters which catch them getting ready for the party, or already on their way there. They are clearly people who inhabit a world light years removed from that of the starving northeasterners down at the train station. But these different worlds soon intertwine.

The novel skips past the party itself to a long concluding section where we learn how the guests were drawn into the net cast by the sinister Department of Political and Social Order (DOPS) as it investigates the train station riot. One after another, their lives, and in some cases, their bodies are shattered as they run the DOPS gauntlet. Of course, the only connection between the party and the riot is in the conspiratorial mind of the DOPS investigators, but that doesn't matter. In a police state, everyone is always guilty of something.

Angelo presents his events and characters through a variety of techniques and styles, like a juggler showing all his tricks. He culls newspaper columns and political speeches for quotes that frame his story. He offers brief biographies reminiscent of John Dos Passos' work, flat narratives which recall Heinrich Boll's dutiful style. We hear one half of phone conversations, staccato interior monologues, an infant grappling with the first steps in constructing sentences.

There are even snippets of notes by the "author" about the novel, ideas for other stories, a reminder to himself to apply for a writing grant, and a conversation with a friend about why he describes the preparations for the party, and its aftermath, but not the party itself. "The book exists without the middle section," he maintains, "but it doesn't prevent me from perceiving the gap in it. Of course, I'm not going to let the reader notice." These interspersed author's notes, by the way, seem a very accurate picture of the crazy jumble of ideas and associations which is the novelist at work.

But with all the experimentation, Angelo's novel is solidly and consciously in the mainstream of Brazilian literary concerns, one of which has always been the great gap of incomprehension between the modern, prosperous coast and the backlands of the northeast, the largest area of absolute poverty in the Western Hemisphere.

It is the same theme Euclides da Cunha treated in 1902 in Rebellion in the Backlands, generally recognized as Brazil's greatest work of literature. In da Cunha's day, the coast sent large armies to the backlands to crush charismatic movements it didn't understand. Angelo's book contains respectful nods to da Cunha and other Brazilian writers, which underline the point that the conditions they described have not changed much. If Latin American writers seem fixated on their history, it may be because they see it repeated in the streets every day.