Audax the hero is a convinced military defender of the Roman Empire. The disasters that he undergoes (serious wound, captivity, loss of wife and child, and conflict with Aetius, his commanding officer) force him to flee to Visigoth territory and the protection of his former captor, King Theodoric. With a new life companion in his new surroundings, Audax becomes a powerful personnage among the barbarians, and discovers unanticipated aspects of responsibilities and allegiances. His complicated life brings him into contact with such historic figures as Germanus of Auxerre, Lupus of Troyes, Hilary of Arles, as well as the mysterious Vortigern in Britain. In a stirring finish, Audax accompanies Theodoric to the battle of Mauriac, where Romans and barbarians join in thrusting back the invader, Attila the Hun.