The show opens with Glinda addressing the citizens of Munchkinland with the news of the Wicked Witch of the West's death. She begins to reminisce about their time spent in school together, where her green-skinned roommate, Elphaba, was studying magic to join with the Wizard in Emerald City.
While at school, they meet a boy named Fiyero who immediately begins to date Glinda, much to the dismay of Elphaba. With her new found friends, Elphaba leaves to go to the Emerald City to talk to the Wizard about the injustices toward the human-like Animals of Oz.
While in the Emerald City, Elphaba learns that the Wizard is the one responsible for the loss of the Animals' civil rights and vows to fight him. Stealing his spell book, she escapes on a flying broom, but not before asking Glinda to come with her. Glinda refuses and the two part ways.
Act 2 opens with Glinda speaking about the troubled times in Oz. The Wizard has spread false rumors about Elphaba and the people all think of her as a witch. Fiyero can't understand why Glinda won't say anything to stop it.
Fiyero decides he has enough and goes to find Elphaba. Their love is short-lived with the arrival of a house from the sky. Elphaba investigates and is trapped by the Wizard's men. Elphaba flees to a castle in the western part of Oz.
Dorothy makes her way to the Emerald City and is given the task to kill the Wicked Witch of the West. Glinda flees to Elphaba to warn her and Elphaba realizes that there is nothing left for her to do. Glinda and Elphaba forgive each other and Elphaba goes to her fate against Dorothy.