The 2004 film, King Arthur, starring Clive Owen and Keira Knightley, introduced the audience to Lucius Artorius Castus as the basis to the much later legend of King Arthur. The book analyses the theories behind the film which link this second to third century Roman officer with the medieval Arthurian legends and a possible historical figure in post-Roman Britain. This first full academic study of Artorius Castus offers a number of potential timeframes and details his career through a turbulent and bloody period of Roman history, serving as primus pilus of V Macedonia and praefectus of the Sixth Legion in northern Britain. Turning to the historical narrative of the film it covers the archaeological and literary evidence for the break down of Roman Britain, arrival of Germanic peoples and emergence of petty kingdoms and new cultural identities. The penultimate chapter lays out the evidence for and against a historical Arthur, offering suggestions as to his identity, location of his battles and the possible political, military, social and cultural situation he lived and fought in. This is an entertaining and informative picture of two fascinating figures, one firmly historical, the other shrouded in myth and legend. The book leaves the reader with a clear picture of the lives of a Roman career officer and later dark-age warrior and the different worlds in which they lived. Anyone interested in the Roman period, post-Roman Britain and the possibilities for a historical Arthur should enjoy this book.