Kara has survived the threat of the Reapers, but at an unspeakable cost—the Archfiends have escaped their eternal prison. Now, with the mortal world on the brink of the apocalypse, with the threat of evil beings as powerful as gods, she must break the rules and travel across the mortal world on an unauthorized mission. Along the way she must face her darkest truth . . . a truth about the change inside her, a truth that she cannot stop.

Meanwhile, the Archfiends and their brutal and monstrous forces are gathering on Earth, intent on enslaving the mortal world, and to destroy Horizon and all the angels. Will Kara find the strength to not only fight her inner demons, but to take on the evil that is about to be unleashed?