PERSIAN NIGHTS<i> by Diane Johnson (Knopf: $17.95; 348 pp.) </i>

Chloe Fowler, wife of a prominent San Francisco surgeon and member in good standing of the medical jet set, arrives in Iran without her husband, expecting that he will soon be joining her. Plans have been made for their five-month stay in Shiraz, where he is to work with a team of visiting physicians at Azami Hospital, and she, thanks to a modest grant obtained through her post as docent at the San Francisco Art Museum, is to study Persian pottery at the local university. At the end of the school year, their two children are to visit them. En route, however, her husband is notified of a medical emergency and decides to return, strangely urging Chloe to go on without him.

The year is 1978, the portentous period before the Iranian Revolution. When Chloe arrives in early spring, there is political unrest but little to indicate that the shah’s regime is on the verge of collapse. Wary yet also exhilarated, she settles into her barren quarters at the Azami Compound, embracing her temporarily single status as a “kind of gift of fate.”

For Chloe at 35--attractive, intelligent and accommodating--has reached that point in her otherwise comfortable, 12-year marriage where she feels that she has “hardly ever, her whole life long, been alone.” What she seeks from the country she has known through art and legend as Persia is “strangeness, a feeling of being far from home,” an escape from “materiality.” Also, “a little in love” with her husband’s dashing colleague, Hugh Monroe, she seeks “an interlude of sweetness.” Her model is Colette, “or European life in general, so civilized, where people don’t divorce, just conduct affairs of the heart discreetly.” Her marriage, she anticipates, will be the better for it.

In time, Chloe has her wish and spends her Persian Nights in sensuality, but not before her experience deepens into mystery, exposing the underside of her whole existence.

Her husband does not come; her lover remains secretive about his previous movements; a social outing to a historic cave turns up an unidentified body, which is then hastily buried in the desert; evidence of a typhoid epidemic is oddly dismissed by the hospital’s chief physician, who is later arrested inexplicably, and, meanwhile, her own quarters are broken into, and she herself comes under increasing suspicion and scrutiny. What to make of these strange developments? And are they in any way interconnected or related to the country’s larger happenings?

All this is material for a tale of high adventure in a dangerous, foreign setting; but novelist and screenwriter Diane Johnson--whose last book was a probing biography of Dashiell Hammett--also explores a deeper level of human intrigue: one that has less to do with the suspenseful action than with its attendant moments of doubt and discovery. Nor is Chloe’s life the only one that is upended here.

Deftly, the narrative weaves through the lives and viewpoints of the other residents of the Azami Compound: Iranian doctors and their fretful, foreign spouses; American doctors divorced or just divorcing; Iranian wives who feel stifled and alienated and seek escape from their country; a grieving widower who seeks meaning in death through an impulsive act of bravery. Each has a separate story that goes its own way, until all are caught in the same collective web of conflict: first through happenstance, then through the onrush of political events. Each, amid the confusion, attempts to make sense of things. But it is Chloe for whom the confusion leads to the deepest questioning.

Abandoned by her husband, whose absence has turned out to be merely a ruse for separating permanently, and guilt-ridden at having neglected her children, she comes to see herself as others see her: “a silly, promiscuous woman” who has been “meddling in the lives of innocent, vulnerable, desperate people.” Her naivete has, in its way, caused as much harm as any deliberate deceit.

“I feel like an idiot,” she declares to her friend, physician Dick Rothblatt, as they are preparing to leave the country.

Dick’s kindly response is that all will be well, once they return to America. “After all, the real world is there.”

But Chloe knows better; the real world is here. That much, at least, she has grasped as a part of her “third-world lesson”: That “locked into a traveler’s capsule,” she has failed “to imagine with sufficient intensity the alien condition.” What, compared with the plight of others, is “the triviality of her own problems?” And what to do, at this late juncture, with this new perspective?

How to fathom the widening gap, or to span it personally, if not by admitting one’s ignorance and getting used to “the whole bleak apparatus of reality?”

“My life has been a flower, what do I know?” Chloe again confesses, at the time of departure.

Yet that admission comes upon still another, only hours before, when Chloe and Hugh are trapped in a mob at Tehran’s Jaleh Square--the site of the Black Friday Massacre, which marked the outbreak of the revolution. Hugh, sensing danger, wishes to leave; but Chloe, indifferent to it, wishes to stay and be carried along, “to try to understand it all” by becoming “a part of history.” The moment is Chloe’s epiphany: She does not want to leave this country during its political awakening. It is all a monumental rite of passage: For Chloe and the country both, a delayed but sudden coming of age.

If there are weaknesses in this taut, compelling novel, they remain secondary to its merits. The Iranian characters tend to be opaque and static, quoting Khayyam and the Koran implausibly in English. Also undeveloped is the political situation, which, even at the end, is viewed obliquely. But more to the point is the novel’s powerful conclusion, which is mitigated by its shift away from Chloe to lesser characters merely to tie up loose ends of the story. Undramatically, all the missing details are narrated by two characters, while waiting to board a plane: Hugh himself, who suddenly sheds his reticence, and a French physician who arrives, deus ex machina , to dispel what little is left of the mystery.

“How neat and tidy,” concludes Hugh, rather smugly.

Quite so. All the pieces fit together like a jigsaw puzzle.

Meanwhile, the heart is aching, along with that of “little, fragile, flowerlike” Chloe, who is the only one who sees beyond the immediate to the larger mystery.