A sequel to Mistress of Rome (and, less directly, Daughters of Rome), Empress of the Seven Hills follows the fortunes of Vibia Sabina, daughter of a noble senator and a selfish spoiled aristocrat, and Vix, son of a barbarian chieftain and a Jewish slave, as their lives intersect and become inextricably entangled with the Emperors Trajan and Hadrian. Vix, feeling stifled by the smallness of life in Brigantia, heads back to Rome, initially taking work in the household of Marcus Norbanus, whom he knows for a good man. The little daughter of the household that he remembered has grown up into a complex and fascinating woman, forthright and unyielding, determined to take charge of her own destiny. They have an affair, but when she decides to marry Hadrian — the Emperor Trajan’s ward, though not yet his heir — trouble arises and they part ways. Vix joins the legions, aiming to be a great general someday. Sabina uses Hadrian as a way to get out and see the world.
The reader then follows Vix on campaign, but he and Sabina collide again when Hadrian comes to serve as legate for Vix’s legion, and their interactions (and the repercussions of those actions) drive a lot of the story as it moves from Germania to Dacia to Parthia. Vix’s and Hadrian’s competing ambitions also fuel conflict; Emperor Trajan thinks highly of Vix and starts pushing him up the ranks, which Hadrian (and his ambitious sort-of-adoptive-mother Plotina) resent.