River of Gods, by Ian McDonald, Pyr, 2006, $25.

BACK IN the day, in honors English, as I watched out the window—dinosaurs tall as the palm trees, New Orleans taking on the sickly sweet reek of springtime magnolia—Dr. Roppolo would talk a lot, as was the fashion then, about appearance and reality. Both dinosaurs and New Orleans are gone now. And some days I don't feel too good myself.

Appearance and reality.

Being and its manifestations. Its avatars.

Science fiction has a many-chambered heart. From its inception it has purported, by exaggeration and anticipation, to predict our futures, to preimagine or prefigure them for us. But it also connects with something much deeper within, reaching down almost casually to that pool of shadow figures and archetypes from which issue all our folktales, religions, and fantasies. It is a literature with its feet planted squarely in the mud of storytelling and its eyes (often quite literally) on the stars. This double strain—the push-pull toward commercialism and its pulp tradition, and toward the literary, prophetic, and fabulist—has constantly driven and re-energized the genre.

Then every so often there comes along a novel, William Gibson's Neuromancer, say, or China Miéville's Perdido Street Station, or Richard K. Morgan's Altered Carbon, that seems to do it all. Extrapolation, a sense of wonder that grabs you by the throat and won't let go, lush carpets of setting, a profusion of ideas, complex representations of characters, soundings of society at every level, all the resources of language.

River of Gods is such a novel.

"The body turns in the stream. Where the new bridge crosses the Gan-ga in five concrete strides, garlands of sticks and plastic snag around the footings; rafts of river flotsam. For a moment the body might join them, a dark hunch in the black stream. The smooth flow of water hauls it, spins it around, shies it feet first through the arch of steel and traffic. Overhead trucks roar across the high spans. Day and night, convoys bright with chrome work, gaudy with gods, storm the bridge into the city, blaring filmi music from their roof speakers. The shallow water shivers."

A dark hunch in the stream. Shies. Gaudy with gods. The river shivers.

And just as Atman gathers, not by unfolding out of some absolute, but from accumulation, from the merging of lower level entities, so does Ian McDonald's novel come together from thousands of paragraphs just like that one.

It is 2047, and India, as of its hundredth birthday, has split into a dozen smaller states. Much of the activity centers around Bharat and its capital Varanasi, perched beside the mighty Ganges that flows from the Himalayas down through plain after plain to the Bay of Bengal. For three years now the monsoon has failed, and water is in perilously short supply. Bharat is on the verge of war (like all wars partly diversionary, partly ideologic, largely economic) with neighboring state Awadh over this, and over an illegally constructed dam. Meanwhile, in desperate hope of affecting climate change, Bengalis tow a vast iceberg toward the Bay of Bengal.

Shiv, moments from stepping onstage in the passage above, is the first we see of the clutch of central characters around whom the events of the novel revolve. He is out harvesting ovaries for sale—yes, the ovaries from that body newly adrift in Mother Ganga. And he is about to discover that his unsavory livelihood has been made redundant by technological advances.

Next we meet Mr. Nandha the ever-so-proper Krishna Cop, on his way to excommunicate an AI that has come into self-awareness at an outlying factory and "turned on its masters," and that must be stopped from escaping or out-copying itself. Sanctions exist against harboring AIs or developing them beyond certain parameters, but there is, of course, a black market in illegals.

"It's an inspection robot, a little clambering spider-monkey thing.… All it knows is that these creatures want to kill it, and it wants to exist."

So it goes, as we meet:

Shaheen Badoor Khan, Muslim assistant to a Hindu Prime Minister, a man secretly drawn to those who have "stepped aside" and had themselves neutered;

Najia, the reporter who snoops out Khan's secret and suddenly finds herself a conduit for much more than the entertainment she has hitherto passed off as (and believed to be) news;

Tal, the nute who helped create the immensely popular soap opera whose virtual star has a virtual "life" apart ("This is the meta-soap department, where Lal Darfan gets the script he doesn't think he follows. It's got to the stage where the meta-soap's as big as the soap itself");

Vishram Ray, the stand-up comic who fled India for Scotland and returns to shepherd the family business's research in zero-point-energy, a business backed by a mysterious investor, research that proves a major fulcrum for the plot;

Lisa Durnau, scientist and creator of Alterre, "the parallel Earth evolving in accelerated time on eleven and a half million Real-World computers," who in a radical sort of eminent domain is scooped up ("vanished") by her own government;

Thomas Lull, Lisa's mentor, now mysteriously vanished himself, and apparently close to the heart of the novel's full mystery;

Aj, rewired, remade as a human interface to the newborn AI calling itself Brahma.

Meanwhile, Mr. Nandha must seek out and excommunicate at all costs that Third Generation AI just manifest in Varanasi.

And then there is the asteroid captured by Earth's gravitational pull, the one with the message from an AI older than the universe itself, a message addressed to three of our characters.

As, all the while, slow missiles creep toward their targets, armor-plated Mercedes cruise blithely past the basest of beggars, debt collection (like war) is carried on by robotic devices outsourced from the U.S. and "manned" by couch-potato gamers, and elective abortion has made women a scarcity in Hindu society, valued ever more highly even as their roles and lives become ever more severely delimited.

Cascades of ideas. A cadence that never lets down, accelerating from its slow opening movements to molto presto. Language synched to the rhythms, the hard trip and fall, of city and heart.

River of Gods clamors and roars and rings and resounds. In form it's a thriller—horizontal, to use Todorov's critical term—but the story's story is very much vertical, penetrating acutely into the lives of its characters and the "life" of a new society.

That society is one of great disparities, unimaginable wealth jutted up against the most unconscionable poverty, technology of the loftiest pedigree developing in buildings below which the superstitious still wash in the Ganges and commit their dead to it.

India, Ian McDonald has said in interview, is an assault on mind, body and spirit. Growing up in Belfast with an Irish mother and Scottish father, he felt always the outsider, developing a lifelong fascination with divided societies, with the wounds and energies they can engender.

"In Belfast, you're left with no doubt that you're at the very butt-end of Empire: Britain's first and last colony. J. G. Ballard is rightly regarded as the sibyl of the Imperial twilight—he writes from the point of view of the colonizer, me from the point of view of the colony."

McDonald freely admits influences, pointing out that all literature is in dialogue with itself, and that, in River of Gods, he quite self-consciously reworked elements from Midnight's Children, A Suitable Boy, and ("of course") Stand on Zanzibar, one of four novels in which John Brunner attemped full-tilt, Balzacian, Dos Passos-like portraits of future societies—politics, scientific advances and shifting cultural "givens," future lifestyles, the textures of the day among every class and at every level of society—in journalistic detail. (The other Brunner novels are Jagged Orbit, The Sheep Look Up, and The Shockwave Rider.)

Brunner was also in some ways a precursor to cyberpunk, the catch-term often used for McDonald's work. In the case of River of Gods, McDonald suggests, instead, khyberpunk—"khyberpunk being to cyberpunk what Bollywood is to Hollywood…something much gaudier and madder."

"Everything," a character notes early in the novel, reflecting on Lal, the virtual soap-opera star with a parallel virtual life, "is a version." Appearance and reality.

And so River of Gods, with rare grace and power, goes about its business, illuminating the fundamental truth at the bedrock of our experience and at the heart of all our folklore, all our religions, the single thing of which we must keep reminding ourselves, the face behind all the masks: that the best of which mankind is capable and the worst are intertwined in each of us: that the figurations of our nightmares so closely resemble the avatars of our dreams.