Most good stories start with a fundamental list of ingredients: the initial situation, conflict, complication, climax, suspense, denouement, and conclusion. Great writers sometimes shake up the recipe and add some spice.
Initial Situation
The Helmers have a seemingly perfect, happy home.
In the beginning, all seems well. Nora and Torvald Helmer appear to be the perfect, happy couple. Torvald is getting a new job managing the bank. They won't have to worry about money ever again. We meet Nora's old friend, Mrs. Christine Linde, who's fallen on hard times. Torvald gives her a job. Also, there's Dr. Rank, a Helmer family friend who is slowly dying from tuberculosis. (So not everything is great.)
Conflict
Krogstad brings trouble. Nora is afraid.
Things start to go bad for Nora when Krogstad shows up. She borrowed money from him and forged a signature in the bargain. Now Torvald wants to fire Krogstad from his job at the bank. He threatens to reveal Nora's little secret if he gets fired.
Complication
Nora begs. Torvald fires. Krogstad blackmails.
Nora begs Torvald not to fire Krogstad. Her begging only makes her husband mad and he fires Krogstad anyway. Krogstad tells Nora that he's going to blackmail both her and Torvald and there's nothing she can do about it. He drops a letter detailing everything in the mailbox. Nora tells Christine her troubles, and Christine runs off to try to talk to Krogstad.
Climax
Nora dances the tarantella.
To stall Torvald from opening the mail, Nora dances a wild and crazy tarantella. She convinces him that he must do nothing but help her practice until they go to a party the next night. For one night at least she is safe.
Suspense
Nora allows Torvald to open the letter.
Krogstad and Christine get together. Krogstad has a change of heart about the blackmail, but Christine tells him to still let Torvald read the letter. She thinks there are too many lies in the Helmer household. Nora and Torvald come home from the party. Dr. Rank stops by to let everybody know he's dying. Nora finally allows Torvald to open the letter.
Denouement
Torvald flips out. Nora severs the marriage.
When Torvald finds out Nora's secret, he flips out on her, saying all kinds of terrible things. Krogstad, overjoyed at being with Christine, sends a letter... saying he's not blackmailing them anymore. Torvald forgives Nora, but she doesn't forgive him. She tells him that they're strangers and that they've never had real marriage. She's been his doll, not his wife.
Conclusion
Torvald hopes. Nora slams the door.
The play concludes with Torvald alone in the room. He seems to have a last-minute revelation. Perhaps he's realized what the most wonderful thing of all really is. We don't know for sure. The last thing we hear is Nora slamming the door as she leaves. Is it really for forever? Who knows? Either way, both Helmers have finally woken up to the emptiness of their lives.