Grace Knox has grown up hearing the folktales of her Irish ancestors, especially about the warriors who fought for control of Ireland. In 19th-century New York City, however, these legends are far from Grace’s mind. She’s much more concerned with how to protect her family from debt collectors, and whether her childhood friend Patrick Devlin will propose. Patrick is a member of the Fenian Brotherhood, a group of young Irish American men intent on fighting for the independence of their homeland, whatever the cost.
Patrick and the Brotherhood use ancient magic to summon mythical warriors to join their fight to protect Ireland. One of them, Diarmid, finds himself drawn to Grace, and she to him. When Diarmid discovers that, in their desperation, the Brotherhood has also summoned a rival group of ancient warriors, he warns Patrick that there will be bloodshed. Grace is caught in the middle of two men she loves, and discovers she alone holds the power to save Ireland - but at a dangerous price.