In a long-ago war, humankind set off a devastating ecological disaster. Thriving indistrial societies disappeared. The earth is slowly submerging beneath the expanding Sea of Corruption, an enormous toxic forest that creates mutant insects and releases a miasma of poisonous spores into the air.At the periphery of the sea, tiny kingdoms are scattered on tiny parcels of land. Here lies the Valley of the Wind, a kingdom of barely 500 citizens; a nation given fragile protection from the decaying sea's poisons by the ocean breezes; and home to Nausicaä.

Nausicaä finds herself on the edge of despair as she comes to realize the full extent of the ecological destruction that's ravaging Earth. Meanwhile, Queen Kushana of Torumekia plots to lead her troops back to the imperial capital and seize the crown. Nausicaä agrees to join Kushana and her people in the fight against the Doroks and her scheming brothers.