WHAT A MAN of many voices is Andre' Brink! He writes with authority from within the minds of his ambassador-hero, his 23-year-old heroine, and in other fiction, a black South African mystic in the 1800s, an Afrikaner farm wife. . . .

Nor do these voices have merely the authenticity -- gift that it is -- of, say, George Higgins or Dylan Thomas or Iris Murdoch, with their unfailing ears. A master technician is at work here, his diverse voices tautening, giving suspense, polishing, building a resilient skeletal structure.

In this sixth novel, Brink, an Afrikaner, moves away from South Africa and its racial insolubles, to a wrenchingly evocative Paris and the insolubles of the human heart.

The ambassador is Pretoria's most brilliant diplomat, at 56, envoy to France. He has been the good soldier, faithful to apartheid policies in which he does not believe, faithful to a wife he does not love, a child he does not understand.

But he is also faithful to the three decade-old memory of a South African gamine, long since dead, a love that led briefly down a freer road from which he turned back.

Enter Nicolette, a young woman much like his lost love, a singer-stripper in a Pigalle boi te, and most dangerously a compulsive flirt who has just ditched the ambassador's ambitious and repressed third secretary. The triangle is established.

If you are interested in an international thriller whose pace is based on terrorists, narcotics deals and machine pistols, this is not your book. Rather, it flowers complexly, enticing you back days later to explore allusions you just realized you had missed.

For beneath the unexceptional plot is a subconscious of literary, biblical and mythic voices that Brink summons by reference and quotation. Clearly by design, they give the book a second dimension of consequence.

For example, early on, the third secretary rhetorically asks, "Why not try to be philosophical and conclude that the Tree of Knowledge bears shrivelled fruit; and sometime or other one has to taste it?"

Forty-eight pages later we see the apple (and a faun and nymph) carved on the apartment house door of his -- and the ambassador's -- inamorata, and 83 pages further on we discover Nicolette eating an apple, leaving her "fresh, clean, sensual white shell-pattern of toothmarks" on it.

This pervading theme of forbidden fruit and punishment is adverted to again through the women with whom the ambassador compares Nicolette: Heloise, Pasiphae, Francesca da Rimini, whose illicit lovers were respectively castrated; driven mad (a bull, he was also victimized by Hercules); and murdered by his brother and consigned to the second circle of Dante's Inferno.

The reference to Francesca connects us unobtrusively with Dante as a whole, who with Baudelaire is the main "hero" of the novel's underlying stream of consciousness. Brink shows us Nicolette's flat, where the lovers are briefly in paradise, then has them descend her stairs to an infernal nighttime Paris.

"With a sigh," says the ambassador, "I follow her down. Reaching the circle of light on the landing below, isolated between darkness and darkness, she glanced back briefly" -- Virgil and Dante, and later on another hint.

They pass the Cafe Alighieri, all boarded up, as if Brink were inviting us to unboard it and compare his work with Dante's masterpiece, to ponder the nature of heaven and hell, of joy, guilt and damnation. At the end of this scene they reach a satanic basement bistro, where Nicolette dances with a "young demon" and the ambassador knows he is in hell.

THE REFERENCES to Baudelaire are as cleanly melded with the surface action and they, too, ingeniously broaden and deepen the novel. As with T.S. Eliot, Brink compares Paris and thus modern Europe with Baudelaire's "fourmillante cite'" haunted by specters and other horrors even at midday.

The ambassador finds a dilapidated paperback of Baudelaire in Nicolette's room which, along with an erotic later reference to the gouffre -- the abyss -- in several of his poems asks us thereby to contemplate Nicolette as Baudelaire's doomed and dooming mistress, Jeanne Duval.

Focusing on the allusions as I have done might make them seem forced. But in the context of a book also extremely readable simply for its perceptiveness, they flow in and out of the narrative with ease, assurance, and pertinence, richly resonating with all we have read and all that Brink has read.

There is one caveat: The Ambassador, despite its art and diligence, will have for some of us a serious failing (although for others even raising the point will seem niggling):

It does not resolve the fate of its hero, not even in the presumptive way that Leopold Bloom and Jake Barnes, and Ce'line's night journeyers are resolved. Having invested so much emotion and interest in the ambassador's faulted decency and brilliant mind, we may resent having to settle for a question mark.

But, on balance, what a settlement! Les Whitten, a former investigator with Jack Anderson, is the author, most recently, of the novel "A Day Without Sunshine."