Teenager Kobi must fight for survival in this post-apocalyptic thriller.Seattle is unrecognizable after the Waste outbreak. A "genetically engineered hormone" initially designed to end the worldwide food shortage has instead infected all life—plants, insects, and animals—and genetically mutated them into gigantic creatures with supernatural abilities, such as the predatory Chokerplants. Kobi and his father are the only known human survivors. They have strict rules in place: Don't spend too much time in the Waste, seal all entrances. Kobi's dad routinely leaves him in their shelter, an abandoned school, to work in his lab for a cure. When he does not return from one of these trips, Kobi must break with protocol and venture out to find out what happened to him. To the Asian-American teen's surprise, he runs into three kids: a white boy named Fionn and two girls, olive-skinned Niki and Indian-American Asha, who are being chaperoned by Guardians, adults in hazmat suits. The action just accelerates from there. The only inhibitor in this tightly and effectively written thriller is the inconsistent science in the worldbuilding. Typically a "hormone" is not spread by "spores" or "cured" by "antibodies." Still, readers will find the plot twists engrossing enough.Ending on a cliffhanger, this book is sure to infect readers' curiosity for a sequel. (Science fiction. 10-14)