Sterling has, perhaps, mellowed a little since he wrote Schismatrix: he's aged and acquired kids, which will mellow even the Youngest and most Turkish of Young Turks, or at least should; discovered how to write characters with not just human but quite sympathetic emotional lives; become an essayist who combines deadly wit and intelligence with a total lack of complacency and a historical sense so strong it's shocking, since most of the people writing about his subjects couldn't tell you the difference between an Anabaptist and a Stakhanovite to save their ration cards. In any case, though Holy Fire has many themes in common with Schismatrix — life-extension, post-humanity, seizing control of the future — it's not the Panzer attack on our sensibilities that the earlier novel was, and this to my mind is a Good Thing.
Sterling imagines a world where true, effective life-extension is common but the really powerful techniques are expensive, even by the standards of late 21st-century technologies and economies. Health care is a combination of a reward for good citizenship and your own personal financial gamble on the life-extension technique of your choice: and almost no one turns down the bargain the world government, the polity, presents. The world in 2095 is full of healthy, powerful, composed, careful people in their seventies, eighties, nineties, hundreds, "gerontocrats." One day one of them, a 94 year old medical economist named Mia Ziemann, has a deathbed reunion with an old college flame, who was not a careful man and so dies only a few decades after his natural time. This sets in motion a train of events culminating in a flash of insight, where Mia realizes her careful life is entirely pointless and lacking in the "holy fire" — last felt, interestingly enough, watching over her daughter's sleep, decades ago. Mia undergoes an experimental rejuvenation procedure which is monstrous enough to be plausible. What emerges has the body and the hormones of a 20 year old, with Mia's memories, but is not Mia, and has no desire to be a well-behaved medical subject. Slipping below the net, she runs away to Europe, calls herself Maya, and finds an illegal niche in the bohemians of various central European cities, people who have "desires which do not accord with the status quo." These are "vivid" people, young, talented (mostly), full of the arrogance and ambition of youth and talent without outlet, scheming to overthrow the foundations of the world. "Her friends were wonderful. She had been very lucky to catch them during the brief larval phase in which they were more or less human. They loved her, and they loved one another, but they loved one another like friends and lovers should and did, and they loved her in the way that one might love a very rare and compelling set of antique portrait photographs."
The plot, frankly, would not be very compelling in other hands, but that doesn't matter, because it's in Sterling's. Maya is believable, not as a 20-year-old girl, which she isn't, but as a 94-year-old post-human creature; and at world-building and world-description, Sterling is unsurpassed. All the thing Sterling describes, and he describes everything from side-walk foods to public-service committees on the net to memory palaces, adds up to a plausible and coherent world. (Those of us who have been following his essays and journalism, and see themes, like civic pride in the Islamic empire, or the connection between bohemia and industrial society, or dead media, turning up transformed in the novel know it all fits because it's all real.) The only reason I didn't read it in one sitting is that my job got in the way.
Someone — maybe even Sterling himself, in some place I can't recall — has said that science fiction is the literature of the industrial revolution, of humanity's ascension to genuine power, and that it asks, if we can do that, what are we to do with ourselves? Holy Fire is the kind of answer that should be given far, far more often.