Ashes by Ilsa J. Bick

A teen with a terminal brain tumor, is in the Michigan wilderness when the "Zap" kills most adults and turns younger survivors into predatory, cannibalistic "Changed." He must navigate a lawless landscape where both humans and nature have become lethally hostile.

This book contains; alcohol, animal cruelty (sadistic)/death, cannibalism, dark content, extreme gore, extreme body horror, extreme horror, mass animal suicide, murder, torture (sadistic), sexual activities (not explicit), suicide ieation, and violence (extreme).