In a post-apocalyptic world devastated by nuclear and chemical weapons, many animal species have evolved to reach a size and level of intelligence close to that of humans. Solo, a young rat raised in this brutal environment, leaves his family so he will no longer burden their limited resources and sets out to find his own path. Faced with predators, cannibals, pirates, and communities willing to do anything to survive, he gradually becomes a formidable fighter. But in a world where violence seems to dictate every choice, Solo must also preserve what remains of his humanity and find a place among his own kind.