The play is set on a mist-obscured fjord in western Norway in the home of Helen Alving. She is a widow and about to open an orphanage in honor of her late husband. Her son, Oswald, an artist who lives in Paris, has returned home for the event. As the play begins, we see Mrs. Alving talking with Manders, the parish pastor. He is depicted as a narrow-minded, hypocritical prig, upbraiding Mrs. Alving for her "modern ideas" and trying to shame her with remembrances of her youth, when she had left her husband. Mrs. Alving, a woman of strength and independence, tells Manders that her husband was an alcoholic and a profligate, and that their life together was misery. She had also left her husband hoping to be welcomed by Manders, whom she truly loved; he seems as unable to acknowledge this as he is to accept the truth about her life with her husband. She had sent Oswald away as a young boy to spare him from his father, and yet has spent the years since her husband's death creating an image of a great man for her son; now they are preparing to commemorate his life with an orphanage. Yet the truth will emerge, and the "ghosts" of the title, both the presence of the dead among the living and the "dead ideas" that haunt the characters, begin to appear.
Two recurrent themes in Ibsen's work are evidenced in this drama. His condemnation of the hypocrisy of society is evident in his mocking portrayal of Manders, the representative of staid, middle-class morality. Ibsen often explored the factor of heredity in determining the personality and fate of the individual. Here, we get a glimpse of the presence of these "ghosts" when Mrs. Alving sees Oswald making sexual advances to the maid, Regina. Years before, she had caught her husband and the maid Joanna in the same situation, and the union had resulted in Regina. Mrs. Alving had quickly found a husband for Joanna and had raised Regina as a servant. When Oswald makes it clear that he wishes to marry Regina, Mrs. Alving is forced to reveal the truth to them. But Oswald's "inheritance" from his father goes farther: he is going mad, a congenital condition acquired through his father. He entreats his mother to help him to commit suicide when his next attack comes; she is horrified at the prospect. As the play closes, the sun has at last broken through the mist, yet the light has come into Oswald's life too late, and he appears lost to the darkness of his mental state. The play is noted for its harsh social criticism and its straight-forward presentation of such controversial topics as adultery, syphilis, and incest, which created of storm of protest when the play first appeared. The symbolism which later dominated Ibsen's work is evident here in the recurrent images of light and darkness.