12-year-old Ted Wiggins lives in Thneedville, a walled city with nothing natural around. One day he surprises his environmentalist friend Audrey with a real tree. Wondering what's happened to nature he asks his grandmother Norma who tells him of the Once-ler. The Once-Ler tells him the story of Mayor Aloysius O'Hare who considers trees and their oxygen a threat to his business. The Once-Ler tells him about the Lorax, the guardian of the world's Truffula trees, and how the mayor had the Once-ler eliminate the tree supply to make a super-useful cloth called the Thneed. Seeing the damage the mass deforestation has done to the environment, Ted and the Once-ler set out to overthrow the mayor and save the last Truffula tree from being killed.