One thousand years have passed since the Seven Days of Fire, an apocalyptic war that destroyed civilization and created the vast Toxic Jungle,[Note 1] a poisonous forest swarming with giant mutant insects. In the kingdom of the Valley of the Wind, a prophecy predicts a saviour “clothed in blue robes, descending onto a golden field, to join bonds with the great Earth and guide the people to the pure lands at last”. Nausicaa, the princess of the Valley of the Wind, explores the jungle and communicates with its creatures, including the gigantic, armored trilobite-like creatures called Ohm.[Note 2] She hopes to understand the jungle and find a way for it and humans to co-exist.
One night, during a visit by the Valley’s swordsmaster Lord Yupa, a cargo aircraft from the kingdom of Tolmekia crashes in the Valley. Nausicaa tries to rescue a passenger, the wounded Princess Lastelle of Pejite, who pleads with Nausicaa to destroy the cargo before dying. The cargo is an embryo of a Giant Warrior, one of the lethal bioweapons that caused the Seven Days of Fire. The Tolmekians, a military state, seized the embryo and Lastelle from Pejite, but their plane was attacked by mutant insects and crashed. One of the insects emerges wounded from the wreckage and seems poised to attack the frightened villagers, but Nausicaa uses a small bullroarer to calm it and guides it away from the Village on her jet-powered glider.
The next morning, Tolmekian troops, led by Princess Kushana and Officer Kurotowa, kill Nausicaa’s father and take the Giant Warrior embryo. Kushana plans to mature the Giant Warrior and use it to burn the Toxic Jungle. Nausicaa kills several Tolmekian soldiers before Yupa intervenes. Kushana announces her decision to leave for Pejite with Nausicaa and five hostages from the Valley. Before they leave, Yupa discovers a secret garden of jungle plants reared by Nausicaa; according to Nausicaa’s findings, plants that grow in clean soil and water are not toxic, but the jungle’s soil has been tainted by humankind.
An agile Pejite interceptor shoots down the Tolmekian ship carrying Kushana and her detachment. It crash-lands in the jungle, disturbing several Ohm, which Nausicaa soothes. She leaves to rescue Asbel, the Pejite pilot and twin brother of Lastelle, but both are swallowed by quicksand and arrive in a non-toxic area below the jungle. Nausicaa realizes that the jungle plants purify the polluted topsoil, producing clean water and soil underground.
Nausicaa and Asbel return to Pejite but find the capital ravaged by insects. A band of surviving Pejites reveal that they lured the creatures to eradicate the Tolmekians, and are doing the same in the Valley to recapture the Giant Warrior. They capture Nausicaa, but with the help of Asbel and his mother, Nausicaa escapes on a glider. While flying home, she finds a team of Pejite soldiers using a wounded baby Ohm to lead a furious herd of thousands of Ohm into the Valley. The Tolmekians deploy tanks and later the Giant Warrior against the herd, but their tanks’ firepower cannot harm the Ohm, and the Giant Warrior, hatched prematurely, disintegrates.
Nausicaa liberates the baby Ohm and gains its trust. Her dress stained by its blue blood, she and the baby Ohm stand before the raging herd and are both run over, killing Nausicaa. The herd calms, and the Ohm use their golden tentacles to revive her. She walks atop the hundreds of golden Ohm tentacles as through golden fields, revealing Nausicaa to be the saviour from the prophecy. The Ohm and Tolmekians leave the Valley and the Pejites remain with the Valley people, helping them to rebuild. Meanwhile, deep underneath the Toxic Jungle, a new non-toxic tree sprouts next to Nausicaa’s lost aviation goggles.