Ancillary Justice is a science fiction novel written by Ann Leckie. It is the first book in the Imperial Radch trilogy, which takes place in a future where an empire rules over multiple star systems. The story follows Breq, a former starship AI who now inhabits a single human body and seeks revenge against the ruler of the empire. Ancillary Justice explores themes of identity, power, and the nature of consciousness. It has received critical acclaim for its unique narrative structure and its exploration of gender and social hierarchies.