Queen of Chaos by Kat Ross (The Fourth Element #3)
Publication date: January 18, 2017
Genres: Fantasy, Young Adult
Persepolae has fallen.
Karnopolis has burned.
As the dark forces of the Undead sweep across what remains of the empire, Nazafareen must obey the summons of a demon queen to save Darius’s father, Victor. Burdened with a power she doesn’t understand and can barely control, Nazafareen embarks on a perilous journey through the shadowlands to the House-Behind-the-Veil. But what awaits her there is worse than she ever imagined…
A thousand leagues away, Tijah leads a group of children on a desperate mission to rescue the prisoners at Gorgon-e Gaz, the stronghold where the oldest daēvas are kept. To get there, they must cross the Great Salt Plain, a parched ruin occupied by the armies of the night. A chance encounter adds a ghost from the past to their number. But will they arrive in time to avert a massacre?
And in the House-Behind-the-Veil, Balthazar and the Prophet Zarathustra discover that they have more in common than meets the eye. But is it enough to redeem the necromancer’s bloodstained soul and thwart his mistress’s plans?
As a final showdown looms with Queen Neblis, the truth of the daēvas’ origins is revealed and three worlds collide in this thrilling conclusion to the Fourth Element series.
Previous books in the series:
About the Author
Kat Ross worked as a journalist at the United Nations for ten years before happily falling back into what she likes best: making stuff up. She lives in Westchester with her kid and a few sleepy cats. Kat is also the author of the dystopian thriller Some Fine Day (Skyscape, 2014), about a world where the sea levels have risen sixty meters. She loves magic, monsters and doomsday scenarios. Preferably with mutants.
The Writer's Inkwell 
This is the first I have heard of this series, but consider my interest captured. Beautiful covers and blurbs.