William Gibson's play The Miracle Worker passed through a number of incarnations, from the 1957 television play, to the 1959 Broadway production, to the 1962 Academy Award–winning film, and several later versions, including two more for television. It is loosely based on Heller Keller's autobiography, The Story of My Life, but there are considerable differences between the two, principally in the presentation of the characters of Keller and her father. The title is based on Mark Twain's reference to Annie Sullivan, Keller's teacher, as a "miracle worker."

A singular characteristic of the play is its dependence on stage directions, which are correspondingly detailed. Since one of the two main characters cannot speak, everything she does must be meticulously described, along with the expressions that reveal her moods and reactions. These extensive stage directions are a feature of the play even in Helen's infancy, when she would not be able to speak anyway. They describe the way in which the passing of time is marked with "a slow tune of distant belfry chimes" and play an important role in characterization, with physical and psychological descriptions of the Keller family and Annie Sullivan.

As the play opens, the tableau of the doctor standing over Helen's crib by lamplight, with thermometer and stethoscope, makes it clear that the baby's life has been in danger. However, the first words of Helen's father, Arthur Keller (or, in the stage directions, simply "Keller," emphasizing his position as the patriarch, since this is also the name of several other characters) are to contradict the doctor's professional opinion with the announcement:

Nonsense, the child's a Keller, she has the constitution of a goat. She'll outlive us all.

Although this may sound like bluster, the doctor agrees that Helen displays a great deal of health and vitality, and Keller's prediction proved correct in fact, as his daughter lived well into her eighties, long enough to experience this play on Broadway (since she wrote in her autobiography that she enjoyed attending the theater, despite being unable to see or hear the actors). Throughout the play, Helen's strong and stubborn character is linked to her father's. He indulges and spoils her partly because he sees the resemblance.

The two areas in which Gibson has most clearly embellished upon the account of Keller's childhood given in her autobiography are his emphasis on her wild, undisciplined behavior, and the conflict over her between members of her family, particularly between Keller and Helen's elder brother, James. Keller (like his daughter) becomes increasingly stubborn as he is faced with opposition, which soon extends to his entire family. Kate, Aunt Ev, and James all try to persuade him to consult Dr. Chisholm in Baltimore, and when Keller refuses and rises to leave, James comments facetiously:

Father stands up, that makes it a fact.

James's sarcasm and detachment are his method of coping with his sister's affliction, which is shown to have a corrosive effect on the whole family, all of whom handle it in different ways. This is why James initially appears hostile to Annie Sullivan, mocking her and failing to do anything to help when Helen locks her in her room. However, it is James who, by finally standing up to his father instead of merely looking on and making ironic comments, becomes Annie's closest ally in working the miracle of the title. When Annie says she is going to make Helen refill the pitcher of water she has just spilled over Annie's dress, she tells Keller to sit down and leave them alone:

Don't smooth anything else out for me, don't interfere in any way! I treat her like a seeing child because I ask her to see, I expect her to see, don't undo what I do!

Aunt Ev says that Keller should not allow an employee to address him in such a presumptuous fashion, but James sides with Annie, peremptorily telling his father:

She's right, Kate's right, I'm right, and you're wrong.

James's decisive act of rebellion against his father gives Annie the chance to work her miracle, which is carefully and poignantly described in the stage directions. When Helen has made the sounds "Wah Wah" and spelled out the word "water" into Annie's hand, Annie drops to her knees as if in prayer. The religious imagery of baptism and purification here is unmistakeable.

When Helen touches her father's hand and Annie spells out the word "papa," it becomes clear that Helen at last understands the relation between the word and the man. Keller and Kate also drop to their knees "stammering, clutching Helen to them." The practical movement of kneeling to reduce themselves to the height of a child again takes on a religious significance, as they give thanks. Annie backs away, and for a few moments, mother, father, and daughter are locked in an embrace, while Helen continues frantically to spell words into Kate's hand to make sense of the cascade of information suddenly engulfing her mind. Very quickly, however, Helen turns and gropes around for the missing figure of her teacher. She finds her and points toward her, enquiring what word she can use to describe Annie, who spells the word "teacher" into her palm.

At this point, Kate relinquishes Helen, who goes to Annie, kissing and embracing her. Kate is "torn both ways" but finally decides to go into the house with Keller, leaving Helen and Annie alone on the stage. The lights are half down now, and Annie spells into her pupil's hand the words "I love Helen. Forever and ever." The play ends with the two entering the house, reuniting Helen with her family for a future in which new horizons have suddenly opened for all of them. Annie has made this possible, a fact acknowledged by both the title of the play and the way in which the mother who gave birth to Helen acknowledges Helen's rebirth through Annie's love, patience, and perseverance.