The play is divided into three acts and the beginning of the first act takes place on the Keller homestead. The smallest child in the family, Helen, survived a terrific accident and her parents are relieved to be told their daughter is going to live. After the doctor leaves, the parents realize, mortified, that their daughter is no longer able to hear or see anything.
The play progresses until Helen is almost seven years old. Many members of the family insist the young child be sent away to an asylum but the mother refuses to accept it. She tries to convince her husband to try one more thing, namely getting help from a well-known doctor who helped many disabled children live a relatively normal life.
The scene changes and Annie is first introduced as a former pupil and patient of Dr. Bell. Annie was blind but after many surgeries, she recovered some of her sight. Now, she was sent to the Keller family to be a governess for Helen. Annie has her own traumatic past, being separated from her brother at a really young age and being abandoned by her parents.
Helen's mother is at the train station waiting for Annie and she is disappointed to learn Annie was not too long ago blind as welL. Still, together with her husband, they decide to give Annie a chance.
When Annie first meets Helen, they get off to a great start. Annie tries to teach Helen to spell two words, doll and cake, and she seems successful in doing so. Helen also manages to lock Annie into her room, making the young governess realize that the child is both extremely intelligent and not someone who can be fooled easily. Still, despite the violent way in which Helen behaved and the disbelief coming from Helen's parents, Annie decided to stay and try to teach Helen everything she can.
The action described in the second act takes place almost completely during one evening when the whole family is having dinner. Annie is shocked to see how Helen is allowed to do everything she wants, touching every plate and eating from everyone's plate. Annie does not allow Helen to eat from her own plate and when the family insists Helen be le to do what she wants, Annie refuses.
Annie convinces the family to leave her alone in the room with the child and she tries to teach Helen some manner. The experience turns violent and in the end, Mr. Keller thinks about sending Annie away. Annie tells them about her past, how she grew up in an asylum and the conditions she had to endure there. The parents agree to give her one more chance and to allow her to do what she wants. Annie asks to be given free rein for two weeks and for no one in the family to have any form of contact with Helen. The two will live in a small house near the main one for two weeks and Annie will be able to do what she wants in an attempt to teach Helen. The second act ends with Helen and Annie alone in a small house, Annie thinking about what she will teach Helen.
The third scene takes place on the day when the two weeks are up. Helen and Annie return to the house and it seems Helen is determined to test what she was thought and to see with what she could get away. Annie is given authority over the young child and when she misbehaves by knocking over a pitcher of water, Annie takes Helen outside to fill it again. Outside, Annie feels disappointed, feeling as if she let down the young girl before her. Helen had yet to understand that Annie was trying to teach her the name of the things around her. However, at the pump, a miracle happens and Helen understands for the first time the connection between what Annie was spelling to her and the things around her.
Everyone in the family comes outside and Helen understands for the first time who her parents are. She then rushes to Annie and embraces her, keeping her close and kissing her. The play ends with Annie holding Helen in her arms and confessing she loves the child before her.
