Asher has been training her entire life to become a Sor-Commander. One day, she'll give her soul to the gilded, mechanical body of the Sor and become a commander to a whole battalion of Dedicates. These soldiers, human bodies encased in exoskeletons, with extra arms, and telepathic subordination to the SorCommanders, are the only thing that's kept the much larger Levastani army of conquest at bay for decades. But while on a training journey, Asher and her party are attacked, and her commander is incapacitated, leaving her alone to lead the unit across a bitterly cold, unstable mountain. Worse, one of the Dedicates is not what they seem: a spy for the enemy, with their own reasons to hate their mechanical body and the people who put them in it. To get off the mountain alive, Asher and her unit will need to decide how much they're willing to sacrifice—and what for.