Ancillary Sword is the second book in the Imperial Radch series, and the first of the Nebula award nominated novels I'm reading this year.
The action picks up immediately after the events of the previous book--a piece of Anaander Mianaai, Lord of the Radch, commissions the single unit left of Justice of Toren as a Fleet Commander and sends her to the system where the sister of her late captain is living. The book centers on events around how Justice of Toren, now Breq Mianaai, dispenses justice and handles events on the station. It's a challenging assignment, since all gates have been closed due to the civil war.
The action in the book builds slowly, though it does get there, and we conclude with some interesting plot revelations for how the series will continue. The real story is in the relationships between the lone ancillary, the AIs instantiated in her ship and the station, and the rest of her crew. The protagonist, being an ancillary, has a high level of access to each crew member's condition through the Ship. So she pretty much sees everything coming. She manages with subtlety.
What's really interesting to me is Leckie's very consistent voice and use of language. The protagonist is uniquely detached, on account of not being human, but still has deep feelings that are consistently from that non-human perspective.
Another fascinating aspect of the series is Leckie's ability to tell a story from a point of view where gender simply doesn't matter. There's no support for it in the Radchaai language, so everyone's a "she", and family relationships always manage to be singular so that the gender is not apparent. The names are thoroughly ungendered as well. She throws in places where the gender differences do matter, just enough to make it clear how much they don't matter elsewhere.
For storytelling, this is three stars, but for the achievement in social speculation through use of language, I give her four stars.