China Miéville turns his pen toward science fiction, in a far-future setting where Earth is a distant memory and the mapping between his version of hyperspace (the “immer”, a term derived from “immerse”, a realm as perilous as Earth’s oceans in the days of sail) and our realm may have your neighbor for trade purposes being in an entirely different galaxy. Our heroine, Avice Benner Cho, is from a backwater world at the edge of navigable hyperspace, where the native Ariekei have a language that requires two separate mouths, working simultaneously to pronounce it. As the story unfolds, we find out that the language has some unusual properties: the Ariekei can’t comprehend the language when synthesized by a machine, and can’t even imagine that a being who doesn’t speak their language is anything more than a pet. And they can’t lie in that language... though humans can. The place where the rest of the universe talks to the Ariekei is Embassytown.
Avice has the talent to become an immerser, crew on a faster-than-light starship, and leaves to seek her fortune. When she returns home, her broader perspective puts her in a position of being able to get involved in events that stem from the surprising things that happen when a species that never knew what lies were begins to learn from a species that is quite good at it. The festivals where humans tell obvious, blatant lies for the amusement of the Ariekei, and the Ariekei attempt to tell their own lies, are just the beginning of a much, much bigger mess.
I have a sneaking suspicion that Miéville never figured out how Ariekei speech works; early on, for example, he establishes that the Ariekei can’t comprehend machine-generated speech, and later on, recordings of speech in their language is significant to the plot. That, and other “wait, what are the rules now?” moments detracted from an otherwise interesting plot.