Snatched from a life of luxury by raiders, Patricius, an adolescent of the Roman-British ruling class, is bundled into one of many boats along with scores of captives. He is bound for a slave-market in Ireland, little more than a collection of petty kingdoms at this point, where a sheep-farming king buys him. Patrick, renamed by his master, is chained to the back of a cart loaded with pigs and his journey to the western edge of the world begins.

Worse than the torment of walking until his feet bleed, is the terrible secret Patrick harbours from his own days as a slave master. It leads Patrick to find God in the desolate Irish hills. Repentance and prayer help to heal his broken spirit, but just as Patrick finally accepts that his permanent future is in Ireland, he is stunned by something that compels him to return to Britain. He becomes a runaway slave, attempting the impossible journey.

Travelling in the dark hours, Patrick secures passage on a merchant vessel and escapes the shores of Ireland. But the boat is bound for Gaul and Patrick is snared in an ordeal worse than his original captivity...