Faced with a coming apocalypse, a woman must reckon with her past to solve a series of sudden and inexplicable deaths in a searing sci-fi thriller from the Compton Crook Award–winning author of The Space Between Worlds. Scales is the best at what she does. She is an enforcer who keeps the peace in Ashtown; a rough, climate-ravaged desert town. But that fragile peace is fractured when a woman is mangled and killed within Ash's borders, right in front of Scales's eyes. Even more incomprehensible is that there was seemingly no murderer. When more mutilated bodies start to turn up, both in Ashtown and in the wealthier, walled-off Wiley City, Scales is tasked with finding the cause—and putting an end to it. She teams up with a frustratingly by-the-books partner and a brusque-but-brilliant scientist in order to uncover the truth, delving into both worlds to track down the invisible killer. But what they find points to something bigger and more corrupt than they could've ever foreseen—and it could spell doom for the entire world.