The last Emperox

Emperox Cardenia Wu-Patrick — Grayland II — has survived multiple assassination and deposition plots, only to find new conspiracies rising in their place. With the Flow streams connecting the Interdependency's star systems collapsing and only the planet End able to sustain unaided human life, the exiled, ruthless Nohamapetan family has seized End and blockaded it to protect their own power, even as billions of refugees have nowhere else to go.

While Nadashe Nohamapetan rallies allies to bring Cardenia down, Cardenia works with her lover Marce Claremont, a physicist chasing a theoretical new Flow stream into End, and her foul-mouthed ally Kiva Lagos to break the blockade and save what's left of civilization. John Scalzi closes out the Interdependency trilogy with political intrigue, hard-science stakes, and his trademark sharp humor.