Short Answer 
The conflict in “A Doll’s House” is introduced through Nora’s secret crime of forgery to secure a loan. Tension escalates with Krogstad’s blackmail, culminating in Torvald discovering the truth, leading Nora to confront her societal oppression and ultimately decide to leave her husband, challenging traditional gender roles.
Step 1: Introduction of Conflict
At the start of “A Doll’s House,” the audience is quickly introduced to a critical conflict involving the protagonist, Nora. She has committed a crime by forging her father’s signature to obtain a loan, a significant act as women had limited rights during this period. This revelation occurs early in the play, establishing an immediate sense of suspense as the audience is aware of her secret while other characters remain oblivious.
Step 2: Building Tension Through Blackmail
The tension intensifies when Krogstad, the man who lent Nora the money, threatens to expose her crime. After being fired by Torvald, Nora’s husband, he uses this knowledge to blackmail her into helping him regain his position. This leads to a gripping scenario where the audience is left wondering how Nora will manage to keep her secret safe amidst multiple crises.
Step 3: Climax and Resolution
The climax occurs when Torvald discovers Nora’s forgery, leading to an emotional confrontation that highlights Nora’s societal oppression. Despite Krogstad’s eventual change of heart, which prevents further blackmail, the damage is done. Faced with humiliation and the realization of her inferior status in her marriage, Nora makes the bold decision to leave Torvald, a revolutionary act that sparks a profound dialogue on gender roles and independence.