The cities of Saint Michael and Saint Selaphiel are under siege from the soul-hunting creatures outside their walls and the corrupt leaders within. Five cities have already disappeared and only two remain. Seventeen-year-olds Colin Kelly and Molly Fitzpatrick yearn to qualify as guardians of their homes, but hurts from their terrible past stand in their way. Five years ago Molly's father murdered Colin's parents. Since then, the would-be-warriors haven't spoken, and while the shame of their family's ruinous legacy has ostracized her, Colin's anger and power-hungry mentor have forged him into anything but a worthy guardian.

After missteps, Molly and Colin end up on-the-run together. In the winter wilderness beyond their protective walls, the two must out-do their pursuers, the creatures, and the brutal cold. To make matters worse, buried secrets stand ready to further shatter their worlds. But if they are going to survive, Molly and Colin must overcome their pasts and work together. Can they forge trust and protect their cities before they are destroyed?