Roman Exit is divided into a series of five chapters, or ‘books’, and follows the life of Vitalinus Vitalis, a Briton from a Romanised, British aristocratic family. His life parallels the period of the Roman departure from Britain and the fall of the Roman Empire in the fifth century AD.
 
Book I tells of Vitalis’ early career as a cavalryman in the Roman Army, first in Britain, then with Magnus Maximus in the general’s attempt to become Roman Emperor of the West. In the service of Maximus, he travels around Europe, becoming involved in some of the major events of the time – intrigue, battles, and encounters with his friend and foe, Aurelius Ambrosius. The book also tells of Vi’s friendship with Maximus and the courting of his daughter, Severa.
 
In the subsequent books, Vitalis eventually returns to Britain and rises in power to the position of Vortigern, supreme leader against the coming of the Angles, Jutes and Saxons.