There are many examples of Nora's secretive nature in the play. In fact, the play is based on her deceit. Here are a few examples divided by the acts.
Act One: Nora secretly eats macaroons behind her husband's back. This sets the tone for the more deceitful deeds she has done. Next, Nora admits to Kristine that she procured the money for their trip to Italy in a devious manner, but doesn't yet tell her how.
Act Two: Krogstad threatens Nora if she doesn't help him keep his position at the bank, and we learn she forged her father's name on the loan.
In Act Three, the truth comes out, and ironically, the truth is liberating for Nora. She finally has the nerve to leave her husband and stand up for herself.
The main conflict of the play is based on the lies Nora has told to her husband. She felt it was necessary to deceive him in order to keep her marriage safe. She had been convinced that she could not survive without him, and Torvald was mainly responsible for this feeling. The irony is that Nora, in trying to maintain her secrets, had learned to be independent. When the truth does come out, she recognizes her own worth.
There are many instances of Nora's deceptive and secretive ways. In the first act , there was the little secret of sneaking a macaroon while Torvald was in his study. He had told her she should not eat any sweets, and so while he was out of the room, she nibbles on it and sticks it in her pocket. Later, she denies that she has gone against his wishes.
Towards the end of Act One, she confides in her friend the deception she created to get money to take the vacation that Torvald needed for his health. She told him that her father had given them the money, but in reality, she had taken a loan. She has never been able to tell him, or anyone else this secret, as she states, "Speak low. Suppose Torvald were to hear! He mustn't on any account--no one in the world must know, Christine, except you."