Even the Darkest Stars by Heather Fawcett

Kamzin has always dreamed of becoming one of the emperor’s royal explorers, the elite climbers tasked with mapping the wintry, mountainous Empire and spying on its enemies. She knows she could be the best in the world if only someone would give her a chance. But everything changes when the mysterious and eccentric River Shara, the greatest explorer ever known, arrives in her village and demands to hire Kamzin—not her older sister, Lusha, as everyone had expected—for his next expedition. This is Kamzin’s chance to prove herself—even though River’s mission to… Read more.