Ghosts (Bokmål: Gengangere) is a play by the Norwegian playwright Henrik Ibsen. It was written in 1881 and first staged in 1882 in Chicago, Illinois, in a production by a Danish company on tour.[1] Like many of Ibsen's plays, Ghosts is a scathing commentary on 19th-century morality. Because of its subject matter, which includes religion, venereal disease, incest and euthanasia,[2] it immediately generated strong controversy and negative criticism. Since then the play has fared better, and is considered a “great play”[3] that historically holds a position of “immense importance”.[4] Theater critic Maurice Valency wrote in 1963, "From the standpoint of modern tragedy Ghosts strikes off in a new direction.... Regular tragedy dealt mainly with the unhappy consequences of breaking the moral code. Ghosts, on the contrary, deals with the consequences of not breaking it."[5]
Helene Alving is about to dedicate an orphanage she has built in the memory of her late husband, Captain Alving. She reveals to Pastor Manders that her marriage was secretly a miserable one, primarily because of her husband's immoral and unfaithful behavior. She has built the orphanage to deplete her husband's wealth so that their son, Oswald, might not inherit anything from him. Pastor Manders had previously advised her to return to her husband despite his philandering, and she followed his advice in the belief that her love for her husband would eventually reform him. But her husband continued his affairs until his death, and Mrs. Alving stayed with him to protect her son from the taint of scandal, and for fear of being shunned by the community.

During the action of the play, she discovers that her son Oswald (whom she had sent away to avoid his being corrupted by his father) is suffering from syphilis that he inherited from his father.[a] She also discovers that Oswald has fallen in love with Regina Engstrand, Mrs. Alving's maid, which is a serious problem because Regina is revealed to be an illegitimate daughter of Captain Alving, and therefore Oswald is falling in love with his half-sister.

A sub-plot that concludes before the play's denouement involves a carpenter, Jacob Engstrand, who married Regina's mother when she was already pregnant (though he is unaware, or pretends to be unaware, that Captain Alving was Regina's father) and regards Regina as his own daughter. Having recently completed his work building Mrs. Alving's orphanage, Engstrand announces his ambition to open a hostel for seafarers. He tries to persuade Regina to leave Mrs. Alving and help him run the hostel, but she refuses. The night before the orphanage is due to be opened, Engstrand asks Pastor Manders to hold a prayer-meeting there. Later that night, the orphanage burns down. Earlier, Manders had persuaded Mrs. Alving not to insure the orphanage, as to do so would imply a lack of faith in divine providence. Engstrand says the blaze was caused by Manders' carelessness with a candle and offers to take the blame, which Manders readily accepts. In gratitude Manders offers to support Engstrand's hostel.

When the sibling relationship between Regina and Oswald is exposed, Regina leaves, and Oswald, who is in love with her, is in a state of despair and anguish. He asks his mother to help him die by an overdose of morphine in order to end his suffering from his disease, which could put him into a helpless vegetative state. She agrees, but only if it becomes necessary. The play concludes with Mrs. Alving having to confront this decision........