Elizabeth Bear's new novel is an exciting and twisty science fiction adventure story. Bear wields several fairly traditional (and not always quite so traditional) SF tropes with expertise: a female-dominated human culture, radical environmentalists killing off most of the Earth's human population, a dueling culture, transcended intelligences, AIs in control of society. This all works very well together, in a story that makes the reader think, makes the reader mad (with perhaps some disquiet), and keeps the reader turning the pages.
In a future after AI "Governors" programmed by radical environmentalists caused the depopulation of Earth, leading to colonization of a variety of other worlds, the Governors and the Earth-dominated "Colonial Coalition" are trying to re-integrated these worlds. Many years after a botched mission to one such world, New Amazonia, they have sent two diplomats to try again - and in particular to negotiate access to this planet's mysterious free energy technology.
The Coalition diplomats are Vincent Katherinessen and Michelangelo Kusanagi-Jones, secretly lovers who have been apart for years after their careers crashed. But New Amazonia's leaders will not negotiate with any but women or what they call "gentle" men. Homosexuality is generally taboo in the Coalition, and women are usually not allowed positions of power, so Vincent and Angelo are the best available choices. New Amazonia, we learn, is ruled by women. Men are kept as slaves, though in better conditions (for the most part) than say blacks in the American Antebellum South. Heterosexual males are matched in Trials: battles, often to the death, with the best chosen to be members of household, where they live in a sort of purdah. "Gentle" males are allowed slightly greater privileges.
The central New Amazonian character is Lesa Pretoria (one small conceit I enjoyed was the use of Old Earth world capitols as family names), an important figure in the Security Directorate. Her family is ranged on the political side urging continued separation from the Coalition. They are also involved in the more local issue of increased rights for males. (Motivated in part by Lesa's concern for her very intelligent young son.) Arrayed against them are the current government leaders, nominally in favor of the status quo, and of some attempt at rapprochement with the Coalition, and possibly secretly aligned with radical groups urging extermination of the male population.
So this is quite a political stew that Vincent and Michelangelo step into. And of course they each have their own secrets - even from each other. The motivations of all of the characters interact complexly, especially as there are not just two but several possible outcomes. And into all this is injected a surprising additional player: a representative of the disappeared original natives of New Amazonia.
It all plays out very entertainingly. There are twists upon twists. There is lots of neat SFnal detail. There is plenty of slam-bang action. Most of all this makes pretty good sense as well ... perhaps there are a couple of holes, but in general things were well explained. The resolution is mostly emotionally satisfying but perhaps a slight letdown - I felt Bear pulled her punches just a bit at the end. Plus, there is something of a deus ex machina aspect to the involvement of New Amazonia's natives - though that's not quite a fair statement as that was all foreshadowed from the beginning, and described in bits and pieces throughout. Carnival is a very fine SF novel, a contemporary SF novel with contemporary concerns that reads like a traditional SF book (in the best sense).
