The Girl of Ink and Stars by Kiran Millwood Hargrave

WINNER OF THE WATERSTONES CHILDREN'S BOOK PRIZE 2017

Forbidden to leave her island, Isabella dreams of the faraway lands her cartographer father once mapped. When her friend disappears, she volunteers to guide the search. The world beyond the walls is a monster-filled wasteland - and beneath the dry rivers and smoking mountains, a fire demon is stirring from its sleep. Soon, following her map, her heart and an ancient myth, Isabella discovers the true end of her journey: to save the island itself.