The Miracle Worker is based on Helen Keller's autobiography. In Tuscumbia, Alabama, an illness renders infant Helen Keller blind, deaf, and consequently mute. Pitied and badly spoiled by her parents, Helen is taught no discipline and, by the age of six, grows into a wild, angry, tantrum-throwing child in control of the household.

Desperate, the Kellers hire Annie Sullivan to serve as governess and teacher for their daughter. After several fierce battles with Helen, Annie convinces the Kellers that she needs two weeks alone with Helen in order to achieve any progress in the girl's education. In this time, Annie teaches Helen discipline through persistence and consistency, and language through hand signals, a double breakthrough that changes Helen's life and has a direct effect on the lives of everyone in the family.