Mary's tone suddenly changes as she reminisces about meeting Tyrone. Tyrone then begins to cry as he thinks back on the memories, and he tells his wife that he loves her. Mary responds, "I love you dear, in spite of everything." But she regrets marrying him because he drinks so much. Mary says she will not forget, but she will try to forgive. She mentions that she was spoiled terribly by her father, and that spoiling made her a bad wife. Tyrone takes a drink, but seeing the bottle has been watered down by his sons trying to fool him into believing that they haven't been drinking, he goes to get a new one. Mary again calls him stingy, but she excuses him to Edmund, telling of how he was abandoned by his father and forced to work at age 10.
Edmund then tells Mary that he has tuberculosis, and Mary immediately begins discrediting Doc Hardy. She will not believe it, and she does not want Edmund to go to a sanatorium. She thinks that Edmund is just blowing things out of the water in an effort to get more attention. Edmund reminds Mary that her own father died of tuberculosis, then comments that it is difficult having a "dope fiend for a mother." He exits, laving Mary alone. She says aloud that she needs more morphine, and she admits that she secretly hopes to overdose and die, but she cannot intentionally do so because the Virgin could never forgive suicide. Tyrone reenters with more whiskey, noting that Jamie could not pick the lock to his liquor cabinet. Mary suddenly bursts out that Edmund will die, but Tyrone assures her that he will be cured in six months. Mary thinks that Edmund hated her because she is a dope fiend. Tyrone comforts her, and Mary once again blames herself for giving birth. Cathleen announces dinner. Mary says she is not hungry and goes to bed. Tyrone knows that she is really going for more drugs.
Act IV, Part One
The time is midnight, and as the act begins a foghorn is heard in the distance. Tyrone sits alone in the living room, drinking and playing solitaire. He is drunk, and soon Edmund enters, also drunk. They argue about keeping the lights on and the cost of the electricity. Tyrone acts stubborn, and Edmund accuses him of believing whatever he wants, including that Shakespeare and Wellington were Irish Catholics. Tyrone grows angry and threatens to beat Edmund, then retracts. He gives up and turns on all the lights. They note that Jamie is still out at the whorehouse. Edmund has just returned from a long walk in the cold night air even though doing so was a bad idea for his health. He states, "To hell with sense! We're all crazy." Edmund tells Tyrone that he loves being in the fog because it lets him live in another world. He pessimistically parodies Shakespeare, saying, "We are such stuff as manure is made of, so let's drink up and forget it. That's more my idea." He quotes then from the French author Baudelaire, saying "be always drunken." He then quotes from Baudelaire about the debauchery in the city in reference to Jamie. Tyrone criticizes all of Edmund's literary tastes; he thinks Edmund should leave literature for God. Tyrone thinks that only Shakespeare avoids being an evil, morbid degenerate.
They hear Mary upstairs moving around, and they discuss her father, who died of tuberculosis. Edmund notes that they only seem to discuss unhappy topics together. They begin to play cards, and Tyrone tells Jamie that even though Mary dreamed of being a nun and a pianist, she did not have the willpower for the former or the skill for the latter; Mary deludes herself. They hear her come downstairs but pretend not to notice. Edmund then blames Tyrone for Mary's morphine addiction because Tyrone hired a cheap quack. Edmund then says he hates Tyrone and blames him for Mary's continued addiction because Tyrone never gave her a home. Tyrone defends himself, but then Edmund says that he thinks that Tyrone believes he will die from consumption. Edmund tells Tyrone that he, Tyrone, spends money only on land, not on his sons. Edmund states that he will die before he will go to a cheap sanatorium.
Tyrone brushes off his comments, saying that Edmund is drunk. But Tyrone promises to send Edmund anywhere he wants to make him better, "within reason." Tyrone tells Edmund that he is prudent with money because he has always had to work for everything he has. Edmund and Jamie, by contrast, have been able to take everything in life for granted. Tyrone thinks that neither of his sons knows the value of money. Edmund, delving into his deeper emotions, reminds Tyrone that he, Edmund, once tried to commit suicide. Tyrone says that Edmund was merely drunk at the time, but Edmund insists he was aware of his actions. Tyrone then begins to cry lightly, telling of his destitute childhood and his terrible father. Tyrone and Edmund, making amends, agree together on a sanatorium for Edmund, a place that is more expensive but substantially better. Tyrone then tells Edmund of his great theatrical mistake that prevented him from becoming widely famous: he sold out to one particular role, and was forever more typecast, making it difficult for him to expand his horizons and find new work. Tyrone says that he only ever really wanted to be an artist, but his hopes were dashed when he sold out to brief commercial success. Edmund begins laughing "at life. It's so damned crazy," thinking of his father as an artist.
Edmund then tells some of his memories, all of which are related to the sea. He reflects on moments when he felt dissolved into or lost in the ocean. He thinks that there is truth and meaning in being lost at sea, and he thinks he should have been born a "seagull or a fish."
Act IV, Part Two
Hearing Jamie approaching the house, Tyrone steps into the next room. Jamie enters, drunk and slurring his speech. He drinks more, but he will not let Edmund drink at first, for health reasons. Jamie complains about Tyrone briefly, then learns of his agreement with Edmund. Jamie says that he spent the evening at the whorehouse, where he paid for a fat whore whom no one else was willing to take. Edmund attacks Jamie with a punch when Jamie begins praising himself and berating others. Jamie thanks him suddenly for straightening him out; he has been messed up by problems related to Mary's addiction. He and Edmund both begin to cry as they think about their mother. Jamie is also worried about Edmund, who may die from consumption. Jamie says that he loves Edmund, and that in a sense he made him what he is at present.
But Jamie also admits that he has been a bad influence, and he says that he did it on purpose. Jamie admits that he has always been jealous of Edmund, and he wanted Edmund to also fail. He set a bad example intentionally and tried to bring Edmund down. He then warns Edmund, saying, "I'll do my damnedest to make you fail," but then he admits, "You're all I've got left." Jamie then passes out.
Tyrone then reenters, having heard all that Jamie said. Tyrone says that he has been issuing the exact same warning to Edmund for many years. Tyrone calls Jamie a "waste." Jamie wakes up suddenly and argues with Tyrone. Jamie and Tyrone both pass out briefly until they are awoken by the sound of Mary playing the piano in the next room. The sound stops, and Mary appears. She is very pale and very clearly on a substantial dose of morphine. Jamie begins to cry, and Tyrone angrily cries that he will throw Jamie out of his house. Mary is hallucinating, thinking that she is back in her childhood. She thinks that she is in a convent. In her hands, she is holding her wedding gown, which she fished out of the attic earlier. She does not hear anyone, and she moves like a sleepwalker. Edmund suddenly tells Mary that he has consumption, but she tells him not to touch her because she wants to be a nun. The three men all pour themselves more alcohol, but before they can drink, Mary begins to speak. She tells them of her talk with Mother Elizabeth, who told her that she should experience life out of the convent before choosing to become a nun. Mary says that she followed that advice, went home to her parents, met and fell in love with James Tyrone, "and was so happy for a time." The boys sit motionless and Tyrone stirs in his chair as the play ends.