Hedda Gabler and her new husband, George Tesman, return from their six-month honeymoon to their new house. We soon learn that Hedda, the daughter of an esteemed general, deigned to marry Tesman only because she had reached the age at which society dictated she should wed. Hedda, not even a year into her marriage, is showing signs of boredom with Tesman even though she's pregnant with his child.
Tesman's Aunt Julia is there to welcome them home. Hedda is quite rude to the older woman, so Julia leaves quickly. After her departure, Mrs. Elvsted arrives to let the Tesmans know that Eilert Lovborg, Tesman's academic nemesis, has returned to town after having fallen into alcoholism and taken two years to achieve sobriety and return to society. Mrs. Elvsted hints to Hedda that she truly loves Lovborg, and doesn't care about her husband anymore - but that she's worried that Lovborg's return to the city will mean that he'll start drinking again.
Judge Brack arrives as soon as Mrs. Elvsted leaves, and lets the Tesmans know that Lovborg has been greeted warmly, and that his new book has been a major success. Indeed, Brack tells Tesman that the professorship he's been expecting might go to Lovborg instead. Privately, Hedda tells Brack that she cares little for her new husband, and that she hopes that the Judge might be able to somehow entertain her during these dull years of marriage. She agrees that Brack will be part of their "triangle" - a relationship that won't necessarily involve explicit adultery, but will provide her with some much-needed companionship.
Tesman returns to the room and says that he's going the stag party that the Judge is holding later that night. Eilert Lovborg soon arrives, and privately confesses his long-held love for Hedda. Once upon a time, they used to be friends, but Lovborg got "too close" and Hedda cut off ties with him - even, at one point, threatening to shoot him. Now he hopes to at least restart a friendship. Mrs. Evlsted arrives, and Hedda mischievously uses the information she has from both parties to pit the two against one another. She makes Mrs. Elvsted look like a fool for having worried that Lovborg would suddenly start drinking again. In retaliation, Lovborg decides to follow Tesman and Brack to their stag party, clutching the pages of the handwritten manuscript for his "revelatory" new book about the future.
Hedda and Mrs. Elvsted wait all night for the men to return, but Tesman doesn't arrive until morning. He is carrying Lovborg's manuscript, which he says the scholar dropped in a fit of late-night drunkenness. Tesman leaves the manuscript with Hedda while he goes out to visit a dying relative, and in the meanwhile, Judge Brack arrives to tell the women that Lovborg got into trouble with the police the night before after assaulting a group of women whom he said took his manuscript.
Lovborg soon arrives and tells Hedda and Mrs. Elvsted that he didn't lose the manuscript, but rather tore it into a thousand pieces. Mrs. Elvsted leaves, devastated that Lovborg has become so self-destructive. Just before leaving, however, Lovborg tells Hedda that he did in fact lose the manuscript. Hedda, who possesses the manuscript herself, says nothing about it, but rather encourages him to follow through on his thoughts of suicide, handing him one of her father's pistols. Lovborg leaves, and Hedda burns the manuscript.
Mrs. Elvsted arrives that night and tells the Tesmans that Lovborg is missing and is rumored to be in the hospital. Brack arrives to confirm the reports that Lovborg has died of a bullet wound to the chest. While Mrs. Elvsted and Tesman sit in the living room trying to reconstruct his manuscript from the notes Mrs. Elvsted possesses, Brack privately tells Hedda that Lovborg did not kill himself, but rather died from a wound inflicted to the bowels - either the result of an accident or someone else's fire. Brack tells Hedda that either she must account for the pistol being hers, or do whatever he tells her to, as only he can keep her from falling into the police's hands or suffering through a public scandal. Realizing that she is now in Brack's power, Hedda goes into the next room and shoots herself.