One thousand years has passed since the Seven Days of Fire, an apocalyptic war that destroyed human civilization and gave birth to the vast
Toxic Jungle, a forest swarming with giant mutant
insects in which everything is lethal to humans. Scattered settlements
exist wherever the Toxic Jungle relents. The Valley of the Wind is one
such settlement. The Valley's settlers have a prophecy stating that a
man "clad in blue and surrounded by fields of gold" will one day reunite
man and nature.
Nausicaä, the agile, cheerful and peace-loving princess
of the Valley of the Wind, has managed to befriend the Toxic Jungle.
She explores the Jungle and communicates with its creatures, including
the gigantic, armored caterpillars/trilobites called Ohmu
, She often travels on a compact jet-powered glider.
One night, a large fixed-wing cargo aircraft
from the kingdom of Tolmekia crashes near the Valley. Nausicaä tries to
rescue an onboard passenger, the wounded Princess Lastelle of Pejite.
She pleads with Nausicaä to destroy the cargo before dying. The cargo is
an embryo of a Giant Warrior, lethal genetically engineered bioweapons
that caused the Seven Days of Fire. Initially discovered by Pejite, the
invading Tolmekians seized the embryo and Lastelle. The Tolmekian plane
however, was attacked by mutant insects before it crashed.
The next morning, Tolmekian troops, led by Princess Kushana and
Officer Kurotowa, subjugate the Valley and secure the Giant Warrior
embryo, killing Nausicaä's sick father in the process. Kushana plans to
mature the Giant Warrior and then use it to burn the Toxic Jungle, even
though history warns of fatal consequences.
Kushana announces her decision to leave for Pejite along with four
hostages, including Nausicaä. Before leaving, Nausicaä's master
discovers her secret garden of jungle plants. According to Nausicaä,
plants that grow in clean soil and water are not toxic. The jungle's
soil, however, has long been tainted by man.
Kushana and her detachment never reach their destination, as an agile Pejite interceptor decimates the entire Tolmekian wing
before being shot down. Nausicaä, Kushana and hostages crash-land in
the jungle, disturbing several Ohmus, which Nausicaä soothes. She then
leaves to rescue Asbel, the Pejite pilot and the twin brother of
Lastelle, but both are swallowed by quicksand and end up in a non-toxic
world below the jungle. Nausicaä realizes that the jungle plants purify
the polluted topsoil, producing clean water that remains hidden
underground.
Nausicaä and Asbel return to Pejite, only to find it ravaged by the
insects. Pejite survivors, boarding a single plane, reveal that they
lured the creatures to eradicate the Tolmekians and would do the same in
the Valley to recapture the Giant Warrior. To prevent any intervention,
they take Nausicaä captive, knocking Asbel out in process. Later, with
the help of Asbel's mother, Nausicaä flees on a glider.
While flying home, Nausicaä finds a team of Pejites using a wounded
baby Ohmu to lead scores of enraged Ohmus into the Valley. Tolmekians
deploy tanks and later the Giant Warrior against the herd to no avail:
tanks prove too weak and the Giant Warrior, hatched ahead of time, soon
disintegrates.
Nausicaä liberates the baby Ohmu and gains its trust, in the process
her pink dress becoming stained in the Ohmu's blue blood turns
completely blue . Both land in front of the herd, but are run over. The
herd, however, calms down. The Ohmus use their golden tentacles to heal
Nausicaä's wounded body. Nausicaä awakens and starts to dance on top of
the hundreds of glowing golden tentacles. Thus Nausicaä, "clad in blue
and surrounded by fields of gold" fulfills the prophecy. Ohmus and
Tolmekians leave the Valley afterward.