The novel describes how, over the course of three days, Julian English destroys himself with a series of impulsive acts, culminating in suicide. O'Hara never gives any obvious cause or explanation for his behavior, which is apparently predestined by his character. Facts about Julian gradually emerge throughout the novel. He is about thirty years old. He is college-educated, owns a well-established Cadillac dealership, and within the Gibbsville community belongs to the prestigious "Lantenengo Street crowd."
Our introduction to him comes seven pages into the novel, in the thoughts of the wife of one of his employees: "She wouldn't trade her life for Caroline English's, not if you paid her. She wondered if Julian and Caroline were having another one of their battle royales". Within the three-day time span of the novel, Julian gets drunk several times. One lyrical long paragraph describes one of his hangovers. During the first of two suicidal reveries, we learn that his greatest fear is that he will eventually lose his wife to another man. Yet within three days, he sexually propositions two women, succeeding once, with an ease and confidence that suggest that this is well-practiced behavior.
On successive days, he commits three impulsive acts, which are serious enough to damage his reputation, his business, and his relationship with his wife. First, he throws a drink in the face of Harry Reilly, a man who, we learn later, is an important investor in his business. The man is a sufficiently well-known Catholic that Julian knows word will spread among the Gibbsville Catholic community, many of whom are his customers.
In a curious device, repeated for each of the incidents, the omniscient narrator never actually shows us the details of the incident. He shows us Julian fantasizing in great detail about throwing the drink; but, we are told, "he knew he would not throw the drink" because he was in financial debt to Harry and because "people would say he was sore because Reilly ... was elaborately attentive to Caroline English". The narrator's vision shifts elsewhere, and several pages later we are surprised to hear a character report "Jeezozz H. Kee-rist! Julian English just threw a highball in Harry Reilly's face!"
The second event occurs at a roadhouse, where Julian goes with his wife and some friends. Julian gets drunk and invites a provocatively-clad woman to go out to his car with him. The woman is, in fact, a gangster's girlfriend, and one of the gangster's men is present, sent to watch her. Both Julian's wife and the gangster's aide see the couple leave. What actually happens in the car is left ambiguous but is unimportant, since all observers assume that a sexual encounter has occurred. There is not any assumption that violence will ensue. However, the gangster is a valued automobile customer who in the past has recommended Julian's dealership to his acquaintances. As Julian is driven home, pretending to be asleep, he "felt the tremendous excitement, the great thrilling lump in the chest and abdomen that comes before the administering of an unknown, well-deserved punishment. He knew he was in for it."
Third, the next day, during lunch at the Gibbsville Club, Julian engages in a complicated brawl with a one-armed war veteran named Froggy Ogden. Julian thought of Froggy as an old friend, but Froggy acknowledges to Julian that he has always detested him and had not wanted Julian's wife (Froggy's cousin) to marry him. In the brawl, which Froggy has arguably started, Julian hits Froggy and at least one of a group of bystanders in the club.
He experiences two suicidal daydreams that oddly contrast with each other. In the first of the two scenes, after Caroline's temporary departure, he places a gun in his mouth:
He does not, however, commit suicide at that time. His second suicidal reverie is after a failed attempt to seduce a woman, the local society reporter. He believes that as a result of his behavior, and the community's sympathy for Caroline, "no girl in Gibbsville—worth having—would risk the loss of reputation which would be her punishment for getting herself identified with him". He believes that even if he divorces Caroline he is destined to spend the rest of his life hearing:
Apparently finding this, and other indications that he had mis-gauged his social status, too much to suffer, he commits suicide by carbon monoxide poisoning, running his car in a closed garage.
Although Julian had many difficulties, some external and many self-inflicted, it seems clear that these difficulties, though serious, were not insurmountable. His wife has departed temporarily for a long talk with her mother, but she and the reader realize that she will forgive Julian. His business had financial difficulties, but they do not seem insoluble. It even seems likely that he could have reconciled with Harry Reilly, who says, on learning of English's suicide, "I liked English and he liked me, otherwise he wouldn't have borrowed money from me... He was a real gentleman. I wonder what in God's name would make him do a thing like that?" and picks up the telephone to order flowers.