From #1 New York Times and #1 USA Today bestselling author P. C. Cast—a passionate and magical epic bringing alive Celtic legend, perfect for romantasy fans who love Sue Lynn Tan and Thea Guanzon and historical fantasy fans of Madeline Miller.

Step into the mystical world of the Isle of Skye in 200 BCE, where legends come to life, goddess and gods walk the mortal earth, and the Queen of Shadow holds court. But Scáthach is no ordinary queen. Daughter of the Underworld goddess Befionn, golden-haired Scáthach is not just a brilliant trainer of warriors, her divine mother has gifted her with the ability to pass between the living world and the Underworld and has granted her dominion over shadows.

Scáthach dedicates her life to training the most talented warriors from across the ancient world at Dunscaith Castle, her impenetrable fortress on the magical Isle of Skye. When Cuchulainn, the Hero of Ulster, son of the Irish god Lugh, arrives asking to become one of her students, Scáthach reluctantly agrees to train him—even though she has serious misgivings about his violent past and the mindless berserker who sleeps within him and whose rage, once awakened, has always been uncontrollable…until the Hero of Ulster meets the Queen of Shadow. Scáthach soon realizes Cuchulainn is much more than the brutal, emotionless warrior everyone expects him to be. And the Hero of Ulster begins to believe he might take control of and even change his foretold fate.

As their growing attraction deepens, Cuchulainn’s father, the God of Light, forces him to retrieve a weapon that will seal Cuchulainn’s fate and forever take him away from the Queen of Shadow. But when Scáthach joins him on the quest through the most dangerous and disturbing parts of the Underworld, Scáthach discovers that her fate may lie in the Underworld and, perhaps, she might be able to forge a future for herself and Cuchulainn by tricking death herself....