The stakes are higher than ever in the third book in Amy Ewing's Lone City trilogy. Revolution is brewing, but Violet has her own battle to win - she must save her sister from the Duchess of the Lake.The Black Key is the third book in Amy Ewing's New York Times bestselling Lone City trilogy, following on from The Jewel and The White Rose. Perfect for fans of The Selection and Red Queen, this shocking and compelling final installment will have readers gripped right up to the final page. Violet and the Society of the Black Key are preparing to launch an attack on the royalty, and Violet has a crucial role to play. She must lead the surrogates as they infiltrate the Auction and change the Lone City for ever. But with her sister, Hazel, imprisoned in the palace of the Lake, Violet is torn. Should she abandon her cause and return to the Jewel if it gives her the chance to save her sister?