The character of Krogstad in A Doll's House contributes to the play in several ways. Krogstad is largely misunderstood and is responsive to the treatment he receives from others which makes him appear untrustworthy and suspicious.
Apart from Krogstad forcing the play to its climax when demanding his job back or the exposure of Nora's secret, he also reveals the hypocrisy that surrounds the business world and the society in which the Helmer's live. Torvald's inability to consider life beyond his strict boundaries and his belief in the structure of the family and each person's part in it, ensure an unfortunate conclusion as Nora is effectively nothing better than a common thief.
Krogstad's involvement reveals how quickly circumstances can change as Torvald goes from wanting to rescue Nora from any harm and wishing "some danger might threaten you (Nora), that I might risk body and soul" to accusing Nora of being "a hypocrite, a liar — worse, worse — a criminal." It is ironic that Krogstad was himself implicated in forgery but escaped punishment, although his reputation was ruined. He is now anxious to retain any good standing he has built up. Torvald however does not believe in second chances and believes Nora is responsible for exposing Torvald: " I am in the power of a scoundrel....And all this disaster and ruin is brought upon me by an unprincipled woman !"
The plot of A Doll's House is further developed by Krogstad's involvement with Mrs Linde, revealing that second chances do exist as their previous misunderstandings and resentments are put aside. Mrs Linde thinks that this will also work for Nora and Torvald and that, through open communication, Nora and Torvald can start again. Unfortunately though, " no man sacrifices his honour, even for one he loves" and so Krogstad's exposure of Nora's secret wil bring the play to its inevitable conclusion.