Mauretania, the second book in Conn Hallinan's powerful Middle Empire series, finds comrades Marcus, Flavius and Demartus leading a daring expedition into northern Africa to rescue a group of their countrymen, among them Marcus's love Aelia, who have been kidnapped and enslaved by Mauri slave traders. They are betrayed by the local authorities and must fight their way through to achieve their mission, in the process becoming mired in the political corruption of a weakened and faltering Roman Empire.