Oswald returns home after decades of living in Paris. He's a painter, and in his return he reveals he's sick and needs caring. Mrs. Alving, his mother, is willing to do so, and she tells him stories about his father, Captain Alving, a hero of his town. In fact, Mrs. Alving is even building an orphanage in his memory, with the help of Mr. Manders, a priest.
But, as Mr. Manders soon discovers, Captain Alving was anything but a saint. Mrs. Alving reveals his husband's reputation was all her doing, hiding the Captain's drunken state, his laziness and being a ladies' man. He even had another child (with another woman), Regina, who is now caretaker of the Alving house.
And Oswald and Regina fall in love. Regina doesn't know he's ill, but Oswald thinks that Regina is the only woman who can heal him from his strange wounds made in Paris (almost certainly, a syphilitic inheritance from his father the Captain). Mrs. Alving and Manders are forced to tell them both the truth: Regina is angry at the revelation, feeling she should've been educated and raised as Alving's daughter and not a servant. Regina learns of Oswald's illness and is relieved she didn't marry him as first intended. She flees along with her father Engstrand, also an employee of the Alvings.
As he lays dying, Oswald wants euthanasia and gives his mother morphia tablets to do the job. She refuses at first, horrified, but then an epiphany strikes her, realizing that helping his son to pass away would be an act of mercy.
This report prepared by Augusto Wong Campos