PERVERSE PSYCHOLOGY

Every novel is an act of audacity, but if any book has ever deserved the catchphrase ''monstrous presumption,'' it would have to be John Irving's A SON OF THE CIRCUS (Random House, $25). Monstrous, that is, both in its immense, stultifying length (633 pages) and in its author's preoccupation with physical deformities and sexual curiosities pretty much for their own sake. Set more or less in India, Irving's eighth novel explores imaginative terrain familiar to admirers of earlier books like The World According to Garp and The Hotel New Hampshire. The novel's protagonist, Dr. Farrokh Daruwalla, an orthopedic surgeon born in Bombay, trained in Vienna, and residing in Toronto, is a man who feels like a foreigner everywhere-but particularly in his native country. Metaphorically speaking, of course, everybody's a foreigner in India, with its many languages and ethnic groups, and its God's plenty of gods, including Hindu, Muslim, Parsi, and Christian. Yet Daruwalla keeps returning to Bombay each year to work with disabled children, to collect blood samples for a research project on dwarfs, and to replenish his imagination for his secret identity as the screenwriter of the hugely successful Inspector Dhar series of Hindi film melodramas. That much said, the intricate story line-which involves dwarfs, transvestites, child prostitutes, self-mutilated eunuch prostitutes, a transsexual serial killer, identical twins who were separated at birth (one is a Bombay film star, the other is a California Jesuit), and a hippie from Iowa married to an Indian homicide detective-is difficult to summarize in this brief space. As always, Irving's ability to keep a seemingly infinite number of narrative balls in the air while dropping nary a one can't help but astonish those readers with sufficient stamina to remain conscious and alert throughout the entire performance. Most readers, however, are apt to agree with the protagonist himself. ''It seemed to Dr. Daruwalla,'' Irving confides toward the conclusion, ''that his story was the opposite of universal; his story was simply strange.'' D