Before the Allegiance came Astridr, whose legend began long before her birth. When the imprisoned seer Sonja is liberated by thirteen Viking warriors, a storm takes the lives of her rescuers and she's left dying and alone. The fae prince Hakon hears her cries - as does Freyja, goddess of the underworld, who arrives to negotiate for Sonja's soul. In love and sacrifice, Sonja survives to bear a daughter, Astridr - while the bargain between the fae prince and the goddess lays the foundation for an immortal's legend.