Rumor Mora fears two things: hellhounds too strong for him to kill, and failure. Jude Welton has two dreams: for humans to stop killing monsters, and for his strange abilities to vanish. But in no reality should a boy raised to love monsters fall for a boy raised to kill them. Nyx Llorca keeps two secrets: the moon speaks to her, and she's in love with her best friend, Dahlia. Braeden Tennant wants two things: to get out from his mother's shadow, and to unlearn his colony's darkest secret. To save everyone they love, they'll both have to commit treason. During one twenty-seven-hour night, these four runaways must stop the war between the colonies and the monsters from becoming a war of extinction, or the things they fear most will be all that's left.