Breq is the only surviving part of Justice of Toren, the sentient AI within a ship of the Radchaai empire. As an ancillary—a human body remodeled, reprogrammed, and then connected to the network of machines and bodies which together made up Toren’s whole self—Breq was just a single appendage acting out the ship-AI’s will. Thousands of years ago, Toren (and therefore Breq) served at the behest of her captain, Awn, and her ultimate master: Anaander Mianaai, Lord of the Radchaai’s interstellar empire. Now, Breq’s orders come only from herself, and she has set out on a singularly ambitious mission with consequences that could split the imperium itself.

Ancillary Justice delights on many levels, exploring themes of identity, loyalty, and status in the midst of interstellar political intrigue, all within an artfully plotted story populated by diverse characters. The Radchaai are a fascinating culture full of contradictions, a mix of unexpected preoccupations and familiar human failings, and Breq’s perspective—not-quite-human but nonetheless fully fleshed out with relationships, interests, and a social consciousness—offers a unique view onto the world’s people and politics. Many of the book’s elements can be found in other sci-fi stories (sentient AIs, mysterious and powerful alien weapons, planetary colonization, and a sprawling space imperium), but author Ann Leckie puts it all together in a way that feels fresh and exciting. The novel’s single weakness lies in its anticlimactic ending, which sets the stage for a sequel but fails to deliver on the expectations established by its epic setting and its protagonist’s daring aims. Nonetheless, it is a thoroughly enjoyable, meaty read that doesn’t make the reader choose between a story that’s smart and one that keeps you up all night just to see what happens on the next page.