Shaking off the disappointment of life's dealing to her, Arianwyn sets out beyond her borders naively unaware of what lies lurking in a world she feels fit to conquest by force of personality.
In Via Acerbum, the second part of the Torc, accompanied by her friend Grainne, Arianwyn the emerging young woman, now devoid of the aid of the Spaewife who has died, is rudely awoken to nature of the world. Capricious choice has denied her Talorcan, her true love, and now realising that Galam, her handfast partner, is a disappointment she jumps at the chance to go draw up a roadmap to peace with King Artuir, her mother's uncle. En route to Gododdin, she and Grainne are enslaved and Galam vanishes. Although rescued from this state on the instigation of King Artuir, he surreptitiously plans to sell her back into slavery on the counsel of Mermin, his religious advisor. As a non-Christian, Arianwyn is expendable and might be best used to finance his quest in appealing to Rome for a legion to command, bring back to Gododdin and return the Pact of Rome to the Isles of Britons.
Plunged into a war-torn Italian countryside during the reign of the Emperor Justinian, nothing goes to plan for anyone. Only Grainne appears to have the strength to bind them through the perplexing adventures that reflect a world in conflict. However, if she should fail, if the Torc constricts Grainne's neck so that she should snap, who then will save them? Who will catch Arianwyn before she slips bodily-beaten and mind-mutilated into Roman gutters?