The Waterless Sea — Kate Constable

Calwyn and her friends have come to the distant Empire of Merithuros to rescue two children who have the magical gift of chantment. But the quest to save the children becomes a struggle for their lives, as it uncovers long-hidden secrets of the man Calwyn loves, and shudders the foundations of the Empire itself. Calwyn will find a way to restore harmony in Merithuros ... but its costs will be as deep as they are unexpected.