Henrik Ibsen's play was published in 1879, and caused a great uproar. His writing is part of the Norwegian Literary Renaissance, and the play itself is not only realist but also feminist. As you can imagine, this caused a bit of a stir with the Victorians. Ibsen was even forced to change the ending of the play in Germany to make it more audience-friendly (more on that later).
Nora is a wife and mother who has never really lived outside of the power of the men in her life. As the play opens, her husband, Torvald Helmer, is teasing her (and when I say teasing I mean openly patronizing) about how much money she runs through during a week. Nora shrugs it off and appeases him; the reader gets the feeling that this is routine. Soon, it is revealed that Nora owes a huge debt to a man named Krogstad, who once loaned her money to save her husband's health (by financing a trip to Italy). She borrowed the money in a panic and has been attempting to pay it off ever since.
Torvald has just been given a promotion, and Krogstad, his subordinate, fears that his job will be eliminated. He threatens Nora and extracts from her that she forged her father's signature on the loan slip (because a woman would have needed either her father or her husband's permission to take out a loan). He says that he will tell Torvald everything if Nora doesn't make certain that he won't lose his job.
Meanwhile, Nora's girlhood friend Kristina has come to see her; she has fallen on hard times and is looking for work. Torvald decides to give Krogstad her job. Dr. Rank, a friend of Nora and Torvald's, tells Nora that he is most likely dying and that he will leave a card with a black cross on it in her mailbox when he is ready to die. He tells her not to tell Torvald because he probably can't handle the news.
Krogstad is fired, despite Nora's efforts, and so he leaves a letter in their mailbox telling Torvald of Nora's crime. Nora confides in Kristina, who seems to have a strange connection with Krogstad (it turns out that the two are old lovers in the end), and then explains that another of Torvald's extremely controlling habits is to keep the key to the mailbox where she can't get it. She decides to distract him from reading it for as long as she can, and so she forces him to help her practice to dance a Tarantella for a party the next night.
After the party, Nora and Torvald return home and find Dr. Rank's business card with the black cross. Then Torvald finds Krogstad's letter and reads it. Nora, who has been hoping for a miracle-- that Torvald might lose his honor for her, and understand her, and truly love her as something besides and object to be possessed-- has an epiphany when Torvald declares that she is a criminal. She decides to leave her husband and children and become an independent woman, for good or bad.
In the alternate ending, Torvald shows her her sleeping children and she decides to stay. This changes the entire meaning of the play, and it's no wonder that Ibsen himself called this an "abomination".
The Doll's House
The major theme of this play is that everyone in it lives in a doll's house, and is a doll themselves. Just as Nora is Torvald's doll, to be played with at whim, so Torvald is society's doll, afraid to love his wife because of what people will think. Nora in her turn plays with her children, dressing them up, leaving them, etc.
Hope or Despair?
One of the things that is ambiguous about the novel is whether it ends on a note of hope, or on one of despair. Has Nora made the right decision in choosing her independence? The point can be debated endlessly.
The play is also titled A Doll House.