Gregers Werle has avoided his father, whom he detests, by spending fifteen years in the family mining concern. Gregers is so unattractive in appearance that he has given up all hope of marrying and having a family; instead, he has become an idealist and goes about advocating and preaching a theme of truth and purity. He calls his mission the "claim of the ideal."
His father, Old Werle, has allegedly driven his sick wife to her death by carrying on love affairs in his own home. He had once had his serving girl, Gina, as his mistress. Arranging her marriage with Hialmar Ekdal, the son of his former partner, Werle also sets the couple up in the profession of photography. Hialmar is pleased with his marriage and believes that Gina's child is his own daughter. At present, Old Werle lives with his housekeeper and between them there are no secrets.
Lieutenant Ekdal, Werle's former partner, is now a broken old man. He does odd jobs for Werle. Earlier, the company had appropriated a large quantity of lumber from a government owned farm. Werle placed all the blame on Ekdal who was sentenced to prison. He is now living with Hialmar and Gina.
Gregers Werle comes to Hialmar and explains the claim of the ideal and tries to make Hialmar see that his marriage is based on a lie. But rather than making Hialmar happy by understanding the true nature of his marriage, Gregers only succeeds in turning Halmar against his daughter, Hedvig. The daughter, in order to prove her love for her father who is rejecting her, takes a pistol and kills herself. Hialmar then becomes bitterly remorseful about his behavior.