Helen Alving is about to dedicate an orphanage she has built in memory of her late husband, Captain Alving. Despite her husband's affairs, Mrs. Alving stayed with him to protect her son Oswald from the taint of scandal and for fear of being shunned by the community.
In the course of the play, she discovers that Oswald (whom she had sent away to avoid his being corrupted by his father) is suffering from syphilis that she believes he inherited from his father.[a] She also discovers that Oswald has fallen in love with her maid Regina Engstrand, who is revealed to be the illegitimate daughter of Captain Alving and is therefore Oswald's half-sister.
A sub-plot involves a carpenter, Jacob Engstrand, who married Regina's mother when she was already pregnant. He regards Regina as his own daughter. He is unaware, or pretends to be, that Captain Alving was Regina's father. 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 open, 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. Manders in turn offers to support Engstrand's hostel.
When Regina and Oswald's sibling relationship is exposed, Regina departs, leaving Oswald in anguish. He asks his mother to help him avoid the late stages of syphilis with a fatal morphine overdose. She agrees, but only if it becomes necessary. The play concludes with Mrs. Alving having to confront the decision of whether or not to euthanize her son in accordance with his wishes.[3]
