THE GOD OF SMALL THINGS.<i> By Arundhati Roy</i> .<i> Random House: 321 pp., $23</i>

A decaying South Indian royalty, its wealth and hegemony in drastic decline, its princess caught in a scandalous affair with an Untouchable carpenter. Punishment, exile, death and the downfall and scattering of the regal line.

Royalty in this case consists of the proprietors of Paradise Pickles, the industrial mainstay of the small Kerala town of Ayemenem. Their tragedy, though, is played out as ornamented princely melodrama: a lush modern fictional equivalent of classical Kathakali theater.

Arundhati Roy, a young Indian writer, has devised a novel of poignancy and considerable sweep, along with some serious weaknesses. Among the appealing elements are a wit that is sardonic and whimsical by turns, a portrait of social change in rural India in mid-century and both sympathy and harsh judgment for a doomed small-town upper class. Above all, Roy evokes the premonitory pain of the two children through whose eyes the story is told--spectators of their family catastrophe and its victims.

“The God of Small Things” is the story of three generations of the Kochamma family. The grandfather, a distinguished entomologist--and a sadistic tyrant within his family--is eclipsed upon his retirement by the enterprise of his hitherto docile wife, Mammaji. She builds a few recipes into a thriving pickle and jam business and makes a family fortune.

Her two children, by contrast, are stumblers. The loquacious Chacko goes off to Oxford on a Rhodes scholarship, marries an Englishwoman, has a child and promptly falls into apathy. After putting up with him for a while, his wife divorces him and marries another man. Chacko returns home and intervenes in the family business with ruinously expansive ideas. Ammu, his beautiful and rebellious sister, has also returned home from a disastrous marriage, bringing two babies, Rahel and her twin brother, Estha.

When the twins are 7, everything falls to pieces. It is the confluence of currents of personal, familial and social decay. Estha, in a scene of brilliant horror, is sexually abused by the candy vendor at a movie house. Ammu, who has lived in a kind of caged heat within the constrictions of the family, has a passionate affair with the factory carpenter, a brilliant, handsome man and a friend of her children. At the same time, Chacko’s ex-wife, now a widow, arrives for a visit along with their beloved little daughter, Sophie.

In a complex, violent climax, Sophie drowns while playing with the twins. Ammu’s affair is discovered. Chacko, distraught with grief and fury, orders her out of the house and separates the twins by sending Estha to live with his father in Calcutta. The carpenter dies from a brutal police beating instigated by a vicious Kochamma aunt. Ammu, living in a furnished room and struggling to make a living, sickens and dies, and the bright and imaginative Estha falls into irrecoverable silence.

The starting point for the story is Rahel’s return, years later, from her own blighted life in America. The house is a ruin; the only ones left are the aunt, who spends the day watching television serials with her maid, and the silent Estha.

Much of “The God of Small Things” is told as the children saw, and failed to see, what went on. There are some beautifully written scenes. The family goes by car to the movies in Cochin, from where they will pick up Chacko’s wife and his daughter the next day at the airport. It is a precursor moment--of Estha’s sexual abuse, the beginning of Ammu’s affair, Sophie’s drowning two weeks later and all that follows.

The car is stopped at a railroad crossing and overtaken by a left-wing political march. With a brief rendering of that heat-stricken wait, Roy weaves together the visible and implicit strands of her story: India at that time and place and two restless children growing into life.

“With a desultory nod of his bored and sleepy head, the Level Crossing Divinity conjured beggars with bandages, men with trays selling pieces of fresh coconut, parippu vadas on banana leaves. And cold drinks. Coca-Cola, Fanta, Rosemilk.” And Rahel and Estha watching, “cloudy children at car windows with yearning marshmallow noses.”

There is a lively portrait of Chacko, the beloved son spoiled by his mother, Mammaji. She is disablingly jealous of Margaret, his English wife. When Margaret comes on a visit, early in the marriage, Mammaji sneaks money into the pockets of her dresses so that she can think of her as a prostitute, not as someone her son loves. Chacko is well-meaning and weak, a spinner of theories. His fearful violence with Ammu at the end comes from the manipulation of his grief by mother and aunt.

There is the heartbreaking moment when Estha is put on the train by Ammu. They hold hands through the window; as the train begins to move, Estha voices his familiar complaint when in need of his mother. “I feel vomity,” he says, as the train bears him off into the night.

Unfortunately, Roy has dressed much of her book in an ambitious gorgeousness that she often lacks the dexterity to manage. She inflates story into epic, the modest magic of perception into an occasional clumsy piece of magic realism, and the erotic current between pickle princess and carpenter into an avalanche, resembling a Hollywood musical crescendo. For example, when they meet the first night at the river:

“Biology designed the dance. Terror timed it. Dictated the rhythm with which their bodies answered each other. . . . Behind them the river pulsed through the darkness, shimmering like wild silk. Yellow bamboo wept. Night’s elbows rested on the water and watched them.”

Roy scrambles chronology, saws her revelations into jigsaw hints and scatters the hints throughout. What in more skillful hands may sustain tension and mystery buckles into narrative cacophony. She bends and teases language. Sometimes the result is a prism that breaks light into new colors; more often, it is a self-reflecting mirror. She will fuse two words into one: “hardsounds,” “wetgreen,” “thunderdarkness”--sucking up the oxygen-pocket that allows an adjective to ignite a noun. Sometimes the noun is sucked up as well: “cementy.”

Inventing as much as evoking her Indian-English patois, Roy invents cute and with cloyed self-indulgence. “Stoppit,” Margaret tells Sophie at one point and, we read, the child “stoppited.” This reader stoppited too, if only for a moment. The book has far too many such moments.