The Deceiver’s Heart by Jennifer A. Nielsen

In this sequel to the instant New York Times bestseller The Traitor’s Game, Kestra Dallisor has finally gained possession of the Olden Blade. With the dagger in her control, she attempts to destroy the tyrannical Lord Endrick. But when Kestra fails, the king strips her of her memory, and leaves her weak and uncertain, bound to obey him. Heartbroken, Simon is desperate to return Kestra to the rebel she was, but refuses to use magic to heal her. With untrusting Coracks and Halderians threatening to capture and kill her, and war looming on the horizon, Kestra and Simon will have to learn to trust each other again if they have any hope of surviving. But can a heart once broken ever be healed?