The waterless sea - Kate Constable

Tremaris is a land divided. From the islands of Firthana, across the deserts of Merithuros to the sinister Black Palace of Hathara, the healing can only begin when the dark magic is unravelled. Calwyn and her friends travel to the Merithuran Empire in search of kidnapped children. They must survive the vast and unforgiving desert and the treacherous Palace of Cobwebs, where they uncover the shameful secret that binds the Empire. Meanwhile, Darrow has formed a dubious alliance with rebels and is marching on the Black Palace. Can he be trusted now that he has the power of the great Ring of Lyonssar? In a stunning climax, Calwyn's actions have greater consequences than she could ever have imagined. This fantastic book takes you through a journey of courage, determination and friendship.