The novel is set in an undefined distant future (although it is implied to exist roughly 5,000 years from now), in which there is a galactic empire spanning eighty worlds, amongst other human civilizations.

The Empire, protected by the Imperial Navy, is at war with a cult of fanatical cyborgs known as the Rix, who worship compound artificial intelligences.

The central characters are Captain Laurent Zai of the Imperial Navy, and Senator Nara Oxham, a member of the Secularist Party, which opposes worship of the Emperor and the use of the symbiont to create immortality.

Publishers Weekly called it "exceptionally smart and empathetic", and noted that Westerfeld "keep(s) the reader constantly off-balance".

[2] SF Signal considered it an "excellent example of space opera", with "strong characters" and "lots of cool technology", but criticized Westerfeld for excessive portrayal of politics.