Caerleon, a small harbour town in the south of Wales, feels very far indeed from the epicentre of the vast, sprawling Roman Empire. The local bishop, Adelfius, has almost given up on his mission to convert the disinterested locals. However, the recent appearance of the devout Jewish Christian Aaron, and the impending arrival of the young, impressionable Roman noble, Julia, might just be the miracle Adelfius needs to put Christianity (and more importantly, himself) on this part of the map.