Kingdom of Sea and Stone by Mara Rutherford

Ever since Nor was forced to go to a nearby kingdom in her sister’s place, she’s wanted nothing more than to return to the place and people she loves. But when her wish comes true, she soon finds herself cast out from both worlds, with a war on the horizon.

As an old enemy resurfaces more powerful than ever, Nor will have to keep the kingdom from falling apart with the help of Prince Talin and Nor’s twin sister, Zadie. There are forces within the world more mysterious than any of them ever guessed—and they’ll need to stay alive long enough to conquer them…