One day the farmhouse, with Dorothy and Toto inside, is caught up in a cyclone and deposited in a field in Munchkin Country, the eastern quadrant of the Land of Oz. The falling house kills the evil ruler of the Munchkins, the Wicked Witch of the East.
In order to return to Kansas, the Good Witch of the North tells Dorothy that she will have to go to the "Emerald City" or "City of Emeralds" and ask the Wizard of Oz to help her. Before she leaves, the Good Witch of the North kisses her on the forehead, giving her magical protection from trouble.
All four of the travelers believe that the Wizard can solve their troubles. The party finds many adventures on their journey together, including overcoming obstacles such as narrow pieces of the yellow brick road, vicious Kalidahs, a river, and the Deadly Poppies.
When the travelers arrive at the Emerald City, they are asked to wear green spectacles by the Guardian of the Gates as long as they remain in the city. The four are the first to ever successfully meet with the Wizard. When each traveler meets with the Wizard, he appears each time as someone or something different. To Dorothy, the Wizard is a giant head; the Scarecrow sees a beautiful woman; the Tin Woodman sees a terrible beast; the Cowardly Lion sees a ball of fire. The Wizard agrees to help each of them—but only if one of them kills the Wicked Witch of the West who rules over the western Winkie Country. The Guardian of the Gates warns them that no one has ever managed to harm the very cunning and cruel Wicked Witch.
As the friends travel across the Winkie Country, the Wicked Witch sees them coming and attempts various ways of killing them.
The Wicked Witch forces Dorothy to do housework for the castle, all the while scheming to steal Dorothy's magical shoes. She also locks up the Lion without food until he will submit to being a pack animal (he never does, as Dorothy sneaks him food at night). When the Wicked Witch gains one of Dorothy's silver shoes by trickery, Dorothy in anger grabs a bucket of water and throws it on the Wicked Witch.
The Wizard provides the Scarecrow with a head full of bran, pins, and needles ("a lot of bran-new brains"), the Tin Woodman with a silk heart stuffed with sawdust, and the Cowardly Lion a potion of "courage". Because of their faith in the Wizard's power, these otherwise useless items provide a focus for their desires.
Having bid her friends farewell one final time, Dorothy knocks her heels together three times, and wishes to return home...