Born with strength no mortal child should possess, Kael was hidden from divine wrath by Lyra, his devoted mother and a sacred seer. Years later, he lives in disgrace within Sparta, mocked as an unwanted heir and forced to bury the power burning inside him. When a Persian commander and his monstrous champion storm the city, they demand Sparta's surrender and seek to carry off Selene, the beloved granddaughter of its elder. After Sparta's defender falls, Kael can no longer remain silent. With golden fire blazing in his gaze, he rescues Selene, crushes the invaders, and becomes the hope of a broken people. But his victory provokes Xerxes himself. As Persia marches toward the frontier, Kael joins three hundred warriors at the narrow pass, ready to face an empire.
