Cold, grey morning light fills the studio; a snowstorm roars outside. Gina is doing housework when Hedvig rushes through the door. She is certain Hialmar is at Relling's. Old Ekdal enters in a dressing gown, and the women tell him Hialmar has gone out.
Gregers appears. He is dismayed that Hialmar is downstairs; he should be collecting his thoughts in solitude. Relling enters and reports that Hialmar is snoring on his sofa. Gina asks Hedwig to help her with the housecleaning.
Gregers asks Relling how he explains the "spiritual tumult" at work in Hialmar. Relling sees none; Gregers is mistaken is idealizing him as some great man. Gregers counters that the aunts who raised him, the "soul mothers" Relling dubs high-flown hysterics, never forgot the claim of the ideal. Relling argues that they are part of Hialmar's illness: in his own circle, he has always been looked on as a "shining light." His handsomeness, "superficially emotional temperament," "sympathetic voice," and talent for declaiming the verses and thoughts of others have always made him appear the "great light of the future." Gregers hardly thinks himself as "stone blind" as Relling believes. Relling disagrees and says that Gregers is sick as well, suffering from an "integrity fever" and a "delirium of hero-worship."
Gregers asks what Relling has prescribed as Hialmar's cure. Relling has given him the usual one: the Livslognen or "life-illusion." He will not reveal Hialmar's particular inoculation but offers Molvik's as an example. Relling has told Molvik he is demonic to save him from self-contempt. Similarly Ekdal has found his own illusion with his fantasies of hunting in the garret.
Gregers sighs in pity; Ekdal has narrowed the ideals of his youth. Relling retorts that he should use a native word, lies, rather than the foreign one, "ideals." The two are as closely related as typhus and putrid fever. Gregers pledges to rescue Hialmar from Relling's clutches.
Relling returns to his flat, and Hedvig re-appears. When Gregers asks if she has yet to kill the duck, Hedvig replies that when she woke this morning, the plan no longer seemed worthwhile. Gregers laments that if only her eyes had been opened to the ideal, and if only she possessed the spirit of sacrifice.