Answer:
Krogstad tries to blackmail Nora into getting Helmer ot keep him at the bank by exposing her forgery.
Step-by-step explanation:
Krogstad has lost his job at the bank and only Nora's father can help him get back his much coveted position. Knowing this, Krogstad approaches Nora and suggests that she talk to her father and ask him to reinstate Krogstad in his position in the bank.
When Nora refuses, the two exchange mild insults until, finally, Krogstad threatens to expose information that will ruin Nora's reputation unless she puts in a good word for him with her father.