The film takes place thousands of years after an apocalyptic war which left nature and humanity unable to live in harmony. The war created a vast forest, called the ‘Toxic Jungle’ which is host to giant mutated insects that threaten humanity.
Nausicaä, the princess of the Valley of the Wind, explores the jungle and communicates with its creatures. She hopes to understand the jungle and find a way for it and humans to co-exist.
The toxic forest was inspired by methyl mercury dumping in Minamata Bay in Japan in the 1950s which caused the area to become toxic and consequently caused the local population to become sick. In the film, the toxicity of the trees evolves as a way to cleanse and purify the world of the pollution the humans had caused.