In the immortal war between gods and demons, one woman's past holds the key to humanity's future. One year after joining the Legion of Angels in New York City, Leda Pierce returns home to visit her family in Purgatory, a rough and rugged frontier town that borders the plains of monsters. Leda's family reunion is cut short, however, when her little sisters are captured by supernatural mercenaries. Together with her angel lover Nero, she sets out to save them. Besieged by monsters, assailed by powerful foes, Leda knows this rescue mission won't be easy. What she doesn't expect is that it will bring her face-to-face with the secrets of her buried past.