When a group of explorers led by the former hunter Fabius discovers a lone boy named Nata wandering the wasteland, they learn he comes from the Forbidden Lands, a harsh and uncharted region long believed to be uninhabited. Nata's people, the Keepers, were driven from their home by the White Wraith, a fearsome monster thought to have gone extinct. To uncover the truth and see the boy safely home, Fabius summons a recently promoted hunter and their feline palico companion to investigate. Together with the guild handler Alma and the blacksmith Gemma, they form the Avis Unit and set out into the unknown. As the expedition ventures deeper into the Forbidden Lands, they aid its native peoples against ferocious monsters and unnatural weather while tracking the elusive creature at the heart of the mystery.