If the acid-blooded, insectlike creatures are hard enough to kill with futuristic weaponry, how much deadlier are they when all you have to fight them with are spears and arrows? Focusing on three young heroes — resourceful Ahiliyah, brainy Creen and brawny Brandun — the novel is gory, visceral and apocalyptic, but amid the blood-soaked battles and shattered limbs it finds time to explore the sociopolitics of survival. Despite a slightly muddled ending, this is a sterling example of how to play interesting new variations on the limited themes of a well-worn franchise.