Queen of Shadows Sarah J. Maas

Everyone Celaena Sardothien loves has been taken from her. But she’s at last returned to the empire—for vengeance, to rescue her once-glorious kingdom, and to confront the shadows of her past…
She has embraced her identity as Aelin Galathynius, Queen of Terrasen. But before she can reclaim her throne, she must fight.
She will fight for her cousin, a warrior prepared to die for her. She will fight for her friend, a young man trapped in an unspeakable prison. And she will fight for her people, enslaved to a brutal king and awaiting their lost queen’s triumphant return.
The fourth volume in the New York Times bestselling series continues Celaena’s epic journey and builds to a passionate, agonizing crescendo that might just shatter her world.