Dusk approaches in the studio. Gina has just taken a photograph of two sweethearts and stands in the doorway bidding them farewell. Hedvig enters, and they wonder why Hialmar has yet to return from his walk with Gregers.
A grim Hialmar returns. He refuses Gina's offer of dinner and announces that he will take up the studio work himself on the morrow. He pledges with disgust to never set into the garret again. Indeed, he almost wants to wring the wild duck's neck. When Hedvig shrieks in horror, he promises to leave it alone. Hialmar is taking up the claims of the ideal, the claims of his soul.
Hialmar urges Hedvig to go out. It is dark enough now, and the vapors in the house are bad for her. Once she has departed, he tells Gina he will also keep the account books himself. He asks her why she never told him his father was so liberally paid by Hakon Werle. Gina first attempts to evade his implicit accusations but ultimately demands that Hialmar explain what Gregers has told him.
Hialmar asks if Gina was Werle's concubine. Gina confesses that when Werle approached her during her service as his servant, she refused. Convinced of her guilt, Werle's wife drove her out of the house. After her death, however, the two became lovers. Hialmar is enraged by her deceit. Gina protests that he would have come to a bad end without a practical wife such as herself. Hialmar moans that he will never finish his invention. The breadwinner's dream of the well-to- do-widow who lives in the wake of his successes will come to naught.
Gregers enters, celebrating the commencement of the couple's new life, a communion founded on truth. He is shocked however by the "dullness, oppression, and gloom" in the household; the "light of transfiguration" should shine from them both. Hialmar should rejoice in forgiving his erring wife and raising her up to someone worthy of love. Gina sarcastically removes the lampshade.
Relling enters and denounces Gregers as a quack. He says that no marriage is based on the claims of the ideal. Relling reminds the Ekdals of the threat their conflict to Hedvig, and at a critical age no less. Gina notes her changing temperament and sees that Hedvig has taken to playing house-on-fire with the stove in the kitchen.