Breq, an Ancillary, is the last remnant of the Artificial Intelligence that was once "Justice of Toren", a star ship built for conquest, with direct control of thousands of conquered human who have been mind-wiped and turned into "Ancillaries".
In the first book of the series "Ancillary Justice" we followed Breq's multi-planet quest for justice, or at least vengence, on the Lord of the Radch who used her to do a terrible thing and then betrayed and destroyed her. It was space opera on a grand scale, with astonishing universe-building that was still mainly about showing how Breq's experiences as a lone, much less powerful, entity shaped her, revealing her honesty and her compassion while honing her anger at everything the Lord of the Radch stood for.
"Ancillary Sword" continues straight on from "Ancillary Justice" but represents a complete change of pace. The Lord of the Radch, who occupies multiple bodies simultaneously across the Empire, is at war with herself. Part of her wants to use Breq as a weapon against the other part and so grants her her House name, accords her the rank of Fleet Captain, gives her command of a Ship, "Mercy of Kalr", staffed with human crew who choose to behave as if they were Ancillaries, and sends her to "Athoek Station", above a planet that produces the best tea in the Empire.
Breq's accepts the mission only because she wants to make amends to the sister of one her own officers on the "Justice of Toren". She arrives at the station and finds it to be a microcosm of The Radch where corruption and exploitation has been allowed to flourish to the edge of introducing slavery.
What follows is almost an inversion of scale from "Ancillary Justice".The focus is no longer on galaxy-spanning hi-tech warfare but on the rituals and civilities that provide the basis for people living together in a peace and on the persistent ability of the privileged to see themselves as the embodiment of culture and civilization while imposing a regime of brutal repression on those they see as inferior.
At first, I found the change in pace disorienting. I kept waiting for a Battle Fleet to arrive. Then I realised that this was really about Breq starting to decide how to relate to the human world. None of the people on the planet or the Station know that Breq is not human, so she builds relationships with them start with her House Name and her rank and grow based on the actions she takes to make the world around her more just.
Breq's relationship with her crew, humans who choose to try to appear as emotionless as the mind-wiped ancillaries, grows as Mercy of Kalr, who knows what Breq is, allows her to see monitor them as she would have her own officers when she was Juster of Toren. Her straighforwardness, her honesty and her refusal to bow to power when it is in the wrong, win the crew's trust and loyalty despite all of Breq's peculiarities.
Breq's relationship with the poor and the privileged and her reactions to the injustices she finds are all part of building her personal vision of how the world should if it were not ruled by The Lord of the Radch.
This is a book driven by the character of the actors. It takes a hard look at what it means to be a person, how power should be used and what justice means.
Of course, in the end, things get blown up and there is action on a spectacular scale but what lingers with me from this book is the power of a tea ceremony to turn what might be bloody conflct into a controlled struggle for power.