Young and innocent fairy Crysta, who calls the rainforest of Ferngully her home, rescues human Zak from an out-of-control logging machine - by shrinking him down to fairy size. Unfortunately, she is unable to return him to his own size, and Zak ends up involved in a fight not only against the loggers who are deforesting Ferngully, but also against the evil Hexxus, who the loggers accidentally free from the tree where he is imprisoned.