The Queen of Nothing - Holly Black

Power is much easier to acquire than it is to hold onto. Jude learned this lesson when she released her control over the wicked king, Cardan, in exchange for immeasurable power.
Now as the exiled mortal Queen of Faerie, Jude is powerless and left reeling from Cardan's betrayal. She bides her time determined to reclaim everything he took from her. Opportunity arrives in the form of her deceptive twin sister, Taryn, whose mortal life is in peril.
Jude must risk venturing back into the treacherous Faerie Court, and confront her lingering feelings for Cardan, if she wishes to save her sister. But Elfhame is not as she left it. War is brewing. As Jude slips deep within enemy lines she becomes ensnared in the conflict's bloody politics.
And, when a dormant yet powerful curse is unleashed, panic spreads throughout the land, forcing her to choose between her ambition and her humanity...
From the #1 New York Times bestselling author Holly Black, comes the highly anticipated and jaw-dropping finale to The Folk of the Air trilogy.