After her adventures with the necromancer in Istanbul, Nadira, now a necromancer herself and the new High Priestess of Elysium, sets out on a journey with her companions to Persia to meet with a mysterious power that dwells in the mountains of Arborz. She intends to learn the secrets of Zoroaster and claim for herself the power over the realms of the dead. She and her companions meet up with the secret remnants of the Nizari Ismaili Assassins and the Sufi mystics who present Nadira with the Books of the Dead to take back to Eleusis. She hopes these books contain what she needs to be able to stop the European powers from igniting a new crusade to reclaim Istanbul and Jerusalem from the Turks. Nadira enlists the aid of the Turkish captain Kemal Reis and his nephew, Piri, on an adventure from the high mountains of Persia to the rough seas of the Mediterranean. The battle for the souls of Europe and Asia involve more than just priests and imams, kings and caliphs.
To stop the slaughter, Nadira must use her power over minds and flesh as well as her quick thinking and courage to bring all the elements together to eradicate the idea of a holy crusade from the minds of the powerful men who rule their world. Her abilities grow with practice and experience, but what she learns muddies the distinction between good and evil. As she becomes more powerful, she begins to lose what it means to be human and starts to take on the guise of a goddess. Her companions wonder if she is becoming an angel of mercy, or a frightening reaper of souls.