Arriving in the ancient Byzantine city in the year 1273, Anna Zarides has only one mission: to prove the innocence of her twin brother, Justinian, who has been exiled to the desert for conspiring to kill Bessarion, a nobleman. Disguising herself as a eunuch named Anastasius, Anna uses her skills as a physician to manoeuver close to the key players involved in her brother's fate. She learns more about Justinian's life and reputation - including his peculiar ties to Bessarion's beautiful widow and his possible role in a plot to overthrow the emperor.