When the sky breaks apart and an earthquake shatters the seaside city of Sharis, cartographer Rukha Masreen is far from home. Caught in the city's ruins with only her tools and her wits, she meets a traveling companion who will change her course forever: the wizard Eshu, who stumbles out of a mirror with hungry ghosts on his heels. He's everything that raises her hackles: high-strung, grandiloquent, stubborn as iron. But he needs to get home, too, and she doesn't want him to have to make the journey alone. As they cross the continent together, though, Rukha and Eshu soon realize that the disaster that's befallen their world is much larger than they could have imagined. The once-vibrant pathways of the Mirrorlands are deserted. Entire cities lie entombed in crystal. And to make matters worse, a wild god is hunting them down. The further they travel from familiar territory, the more their fragile new friendship cracks under the strain. To survive the end of their world, Rukha and Eshu will need more than magic and science—they'll need each other.