When seventeen year-old Kara Nightingale is suddenly struck by lightning and dies—yet again—she finds herself back in Horizon, where angels, oracles and other supernatural beings occupy a mystical world unknown to humanity. But when Kara accidently strikes an angel with her newfound powers and nearly kills him, she is banished to the angel prison Tartarus. What’s more, Kara soon discovers her mother’s soul has been taken by Demons. Hunted by the Legion, Kara takes refuge with a new band of angel friends. She finds herself torn with her feelings for David—when angel romance is forbidden. And when Kara decides to venture into the Netherworld to find her mother’s missing soul, will her powers be enough to save her mother and save the mortal world?