THE BOOK OF ABSENT PEOPLE. By Taghi Modarressi. Doubleday. 206 pp. $15.95.

BEFORE THE REMEDIAL geography lessons of the late '70s -- "Here is Iran between Russia and the Persian Gulf" -- and before our televised cultural education -- "Many of these people chanting 'Death to America' are Shiite Moslems" -- Iranians were to most Americans an absent people, governed by a shah, sometimes seen skiing in Switzerland, who, it was rumored, made some subjects disappear into his political prisons. Now that propaganda has replaced ignorance, Iranians are no less absent to us.

Taghi Modarressi's novel helps fill the void. He creates a large clan of people with their own fingerprints and desires, with individual histories and a shared present, the Tehran of 1963, a time of popular uprisings against the shah. Born and educated in Iran, the author of two novels in Persian, Modarressi first came to the United States in 1959, trained as a child psychiatrist, and lives now in Maryland. If, for readers, his characters are far away and alien, Modarressi too is absent, an exile who can only remember and imagine, not rejoin, his people and native place.

The Book of Absent People is told by Rokni Nezami, a 23-year-old art student who, at the end of his account, leaves Iran. The novel's action takes place within a few weeks and has as its framing events Rokni's father's retirement from medicine and his death. This domestic upheaval forces Rokni back into a family past previously absent to him, a past he finds connected to a hundred years of Iranian history and to the then current violence in Tehran streets.

Rokni discovers that the generations-old clan split -- between the realistic, hard-working and respectable Nezamis and the artistic, passionate and convention-defying Azharis -- is not due to the genetic difference he assumed but is the result of a political argument between brothers over foreign influence in 19th-century Iran. Closer to home, Rokni also learns that his respected "Khan Papa Doctor" once participated in a peasant slaughter and that the doctor's first wife, the Russian-born Homayundokht Azhdari, killed herself because she, as a "foreigner," was ostracized by Nezami women.

THE DYING doctor asks Rokni to find his first-born son, Rokni's half-brother Zia, absent for 11 years after being arrested by the Shah's secret police. To find Zia, Rokni has to investigate present-day politics and needs help from the suspect Azhdaris -- from Masoud, a childhood friend now a SAVAK agent; from cousin Massibi, who sells opium and gives away, perhaps, secrets. Even more important, to unwind the novel's several plots and discover his own identity, Rokni must learn from women, the longest absent people: a half-sister sunken into mental illness, his provincial mother hiding behind her veil, and his long-neglected aunt Badi Zaman, family interpreter of the Koran.

The book's authority -- the presence and import of its people -- comes from the combination of Rokni's innocence, his naive questioning and recording in a voice accented with the youthful simplicity of non-native English, and Modarressi's sophistication, his suspenseful plotting and careful twisting of Rokni's family recognitions into clan complexities and national knots.

Early in his story. Rokni confesses to talking as if he "were reading from an ancient tale." Paradoxically, it is this "bookishness" that expresses the elaborate formalities of a culture with strong remnants of oral traditions and clan relations. Rokni alludes to unfamiliar texts, historical events, and customs without explaining them, another way for the author to create insider authority. Modarressi also has Rokni use Persian forms of address, verbal tags, and folk sayngs, though occasionally American colloquialisms (such as "stick it to him") slip in and disrupt the effect. Because Rokni believes in religious visions and cultural mysteries, a Persian magic suffuses his whole account. In Modarressi's narrator the Azhdaris' art and the Nezamis' social awareness fuse to produce a complex version of the Iranian -- an Iranian's -- mind.

It seems fair to ask who has been left out of The Book of Absent People. Modarressi records an aristocracy "decaying" into an elite professional and civil servant class, the Iranians seemingly best served by the shah's policies. Had Modarressi included other people -- the Tudeh Communists, peasants, or Islamic fundamentalists -- the internal conflicts of the Nezami-Azhdari clan, its split loyalties to various visions of what Iran could be, would have been more comprehensible. Another exile with a family background similar to Rokni's, Vladimir Nabokov, chose to enshrine his memories of Russia with inward-turning art. Modarressi's effect is centrifugal: sending the reader outward from Rokni to his family and, finally, to the library. An intervening stage between his invented clan and historical facts -- other absent people -- would have made this fine novel a better book.