Ghosts is a scathing depiction of 19th-century morality by Norwegian playwright Henrik Ibsen. The play starts off with all the characters convening in the remote town of Rosenvold where Mrs. Alving is dedicating an orphanage to her late husband’s memory. Regina, Mrs. Alving’s maid is working on the garden as her father Engstrand walks in. He tells his daughter that he’s leaving for town and wants her to come with him. He’s saved up quite a bit of money working as a carpenter for the orphanage and intends to open his own “Sailors’ hotel” with it. Upon further discussion, Enstrand reveals that his establishment might not be the most honorable kind. He implies that it’s going to be a high-class brothel and Regina could find herself a suitable sailor there. They argue as Regina refuses to leave with her father because of her ambitions and thinks that working at his father’s establishment might be a step backward. Engstrand leaves unhappily while Pastor Manders enters.
Pastor Manders, an old friend of Mrs. Alving’s has come to review the final details of the orphanage with her. He chats with Regina briefly about going with her father before asking to see Mrs. Alving. Mrs. Alving welcomes the pastor and they talk about the proceedings for the orphanage. Pastor Manders agrees to be in charge of the foundations’ affairs upon Mrs. Alving’s request. When on the topic of insuring the orphanage, Mrs. Alving mentions Engstram’s carelessness with matches and how the building almost caught on fire last night. The pastor warns her that it may look like they have no faith in god if they have insurance. He fears how it might look on his part and manages to convince Mrs. Alving to go without insurance.
At this point, Oswald, Mrs. Alving’s son comes downstairs smoking a pipe. Mrs. Alving had sent Oswald away at the age of seven and since then he’s had a rather successful career as an artist. Oswald only remembers his father through his mother’s letters where he was described as nothing short of an ideal husband and father. He reminisces about the time his father made him smoke a pipe as a child before Pastor Manders interrupts him. As Pastor Manders points out the uncanny resemblance between the son and his late father, Mrs. Alving seems flustered. She quickly changes the topic to talk about how glad she is that Oswald will finally be at home for a while. Pastor Manders and she argue about his upbringing and whether or not she sent him out into the world far too soon. Pastor Manders thinks that he’s never been in a proper home to which Oswald disagrees. As Oswald describes his bustling lifestyle in Europe, Pastor Manders is taken aback. Being a conservative person, he disapproves of Oswald’s bohemian lifestyle and looks to Mrs. Alving for reinforcement. But she too confesses that she shares in her son’s point of view and tells him that she thinks that immorality exists in conservative societies as well. Oswald goes for a walk leaving Mrs. Alving and the Pastor to talk.
Pastor Manders inquires about Mrs. Alving’s reading material and points out how the books are too inappropriate for his taste. She replies that the books mirror her own thoughts. He chastises her radical thinking and reminds her of the time she ran away, a year into her marriage and sought refuge with him. He’s thankful to have been able to convince her to return to her husband and points out to how well it worked out. She then refutes his statement and reveals the truth behind her marriage. Mr. Alving lived dissolutely and died as profligate as he always had been. She had come back to her husband back then but spent the next twenty years covering up for him to protect her son from the taint of scandal. The Pastor is shocked as she goes on about his drinking, his philandering and his sickness. She had sent her son away to ensure that he didn’t follow his father’s footsteps. She’s built the orphanage to completely deplete her husband’s funds so Oswald can get only what’s hers and hers alone. As Pastor Manders learns about Mr. Alving’s debauchery, he finds out that Mrs. Alving had found her husband with their maid Johanna and Regina is the result of their illegitimate relationship. Johanna was married to Engstrand for a hefty amount of money, so they could avoid scandal. Their conversation gets interrupted as Oswald can’t go for a walk due to the rain. As Mrs. Alving enters the next room, she notices Oswald flirting with Regina and walks away as if she saw ghosts.
After dinner, Mrs. Alving and Manders have an urgent conversation. Mrs. Alving wishes she told Oswald the truth about his father. The pastor warns her about her duty to uphold the father’s image in her son’s eyes. But since Oswald is getting closer to Regina, Mrs. Alving fears that she has no choice but to disclose the truth to her son. She goes to the next room leaving the pastor to contemplate whether he made the right decision when he sent her back to her husband all those years back. Mrs. Alving blames him for what he did and he was too scared of being shunned by the society and thought it was appropriate to resist temptation and send her back. Engstrand enters and disrupts his thoughts to ask him to do a prayer service for the new orphanage. Pastor Manders feeling duped because he officiated Engstrand and Johanna’s marriage, asks Engstrand why he lied to the pastor about Regina. Engstrand answers slyly with a made-up story about how he did everything to protect Johanna’s reputation. He also adds that the money he got for the marriage was spent on Regina’s education. The pastor feels bad about admonishing Engstrand and tells him that he will consider investing in his Sailors’ hotel as they leave for the prayer service.
In the next room, Oswald is restless because he can’t work. He comes in and talks to Mrs. Alving and ends up revealing that he is sick. He has syphilis and a Parisian doctor told him that it’s because of his “Father’s sins”. He’s filled with regret as his father was an ideal man and his sickness was brought onto him by himself. Mrs. Alving tries to control her urge to tell her son everything. Oswald tells his mother that he wants to marry Regina. Right at that moment, Regina enters the room with champagne and glasses. Oswald asks her to have a drink with him, which makes both Regina and Mrs. Alving a little uncomfortable. As Oswald talks about the joys of life, Mrs. Alving stands up, prepared to tell them the truth only to be stopped by shouts coming from the orphanage. As they rush down there they see the uninsured orphanage, now on fire.
The pastor is startled beyond words as the orphanage burns to the ground. Mrs. Alving seems quite relieved as the newly built orphanage lies in ashes. She goes out to look for Oswald as Engstrand accuses Manders of being irresponsible with the prayer candles and therefore setting the fire. The pastor is sweating and struggling as he fears that the papers won’t take too kindly to him. Engstrand tells him that he’s willing to take the blame for it as long as the pastor invests in his hotel for sailors. The pastor after a slight hesitation agrees to the arrangement and decides to travel with Engstrand. Mrs. Alving comes back in without Oswald and asks Pastor Manders to take care of the rest of Mr. Alving’s funds. Engstrand exclaims how his establishment would be the perfect memorial for Oswald’s late father as he sets off towards town with the pastor.
Oswald comes in feverish and ill. Regina sees Oswald in his current state and becomes disheartened. Mrs. Alving comes in and sits them both down. She discloses the full truth to both of them. Regina feels betrayed and cheated. She wants out of this sickness and leaves instantly. Oswald is left unaffected. With Regina leaving, he tells his mother about his constantly declining health and the severity of it. He tells her about how the next attack on his brain is going to leave him in a vegetative state and wants his mother to help him end his life with morphine when that happens. Mrs. Alving is stunned at the thought of euthanizing her son but agrees to it hoping that she never has to do such a thing. Oswald calms down and goes to sleep.
As the day wears on, Mrs. Alving and Oswald are the only ones left in the house. She turns off the lamp in her son’s room. At sunrise, Oswald starts relapsing. He starts mumbling nonsense as he slumps into a vegetative state. Mrs. Alving is left with the dilemma of whether to honor her son's wishes and take her own son’s life or leave him suffering.