Lady Mara of the Acoma clan, named Servant of the Empire by Ichindar, Emperor of the Tsuranuanni, whom she has raised from figurehead to true ruler, feels safe from her enemies for the first time in her life -- until an assassination attempt aimed at her kills her young son and heir instead.

Convinced her old foe, Jiro of the House Anasati, is behind the deed, she plans war. But her desires are thwarted by the reactionary Assembly of Magicians, who are, Mara begins to understand, the true power in the Empire, having kept the people docile for a millennium.

In her fight to bring down her enemies and ensure peace for the Empire, Mara must employ the nonhuman cho-ja and an ancient secret.