The Vicario twins later tell the narrator that they began looking for Santiago Nasar at Maria Alejandrina Cervantes' place, where they had been with him until two o'clock. Since he wasn't there, they went to Clothilde Armenta's milk shop, which was near Santiago's house, to wait for him to come out.
After Angela Vicario reveals Santiago's name to her brothers, they immediately go to the pigsty. They pick out the two best knives, wrap them in rags, and have them sharpened at the meat market. Faustino Santos, a butcher, wonders why they are coming—he thought they were so drunk that they didn't know what time or what day it was. They talk about the wedding, and Pablo declares that they are going to kill Santiago Nasar. Because the twins are known to be good people, nobody pays any attention to them. After they leave, Faustino reports the conversation to a police officer who comes by.
At Clothilde Armenta's milk shop, the twins drink two bottles of cane liquor. They tell her that they are looking for Santiago to kill him. Clothilde tells her husband, Don Rogelio de la Flor, but he responds that she is being silly.
Meanwhile, the police officer informs Colonel Lazaro Aponte about the Vicario brothers' plan. The Colonel has settled so many fights the night before that he is in no hurry to settle another. The Colonel hears that Angela Vicario had been brought home on her wedding night, and realizes the connection between that event and the impending murder. The Colonel goes to Clothilde Armenta's shop, takes the knives away from the boys, and tells them to go home. He explains later that he thought the twins were bluffing.
The Vicario brothers go home, get two different knives, and go to have them sharpened. Faustino is confused, believing that the boys have brought the same knives. Although Pedro makes the decision to kill Santiago, Pablo insists on following through with the plan. Pablo Vicario's fiancée, Prudencia Cotes, says she never would have married him if he hadn't upheld his sister's honor by killing Santiago. She waits the three years he is in jail, and when he gets out he becomes her husband for life.
The twins go back to the milk shop, their knives wrapped in newspaper from Prudencia's house. Clothilde Armenta gives them rum, hoping to make them so drunk they can't do anything.
The narrator then describes Maria Alejandrina Cervantes' house, where there are musicians, a dancing courtyard, and "pleasurable mulatto girls." The girls have all been working without rest for three days, taking care of all who were "unsated" by the wedding bash. The narrator says it was Maria who did away with his generation's virginity.
But on the night before the murder, Maria wouldn't let Santiago dress up her mulatto girls as he usually did, so Santiago and Cristo Bedoya and Luis Enrique and the narrator set off with the musicians on a round of serenades. The first house they stop at is the newlyweds', though they don't know that only Bayardo San Roman is there at that point. They all go to get breakfast, but Santiago says he wants to get an hour of sleep before the bishop comes.
Clothilde Armenta has told Father Carmen Amador about the Vicarios' plan, but because of the Bishop's arrival, the Father forgets, and, on his way to meet the bishop's boat, walks right by the milk shop where the murderers are waiting.
This chapter relates the events on the evening of the wedding, the night before Santiago Nasar's death. This chapter chronologically precedes the first chapter of the book. This disjunction in time indicates the temporal confusion within the story as a whole. The first chapter tells about the morning of the assassination, and the third chapter relates the events leading up to that morning.
The novel explores the complexities of the concept of honor. The Vicario brothers believe themselves to be defending the honor of their sister and family, which is so important to them that they kill a man to preserve it. The severity of their crime reflects the severity of the limits imposed upon women. The brothers reason that since whoever took Angela's virginity ruined her chances of finding a suitable husband, that man must be punished with a comparable degree of severity. Even after Santiago is killed, Angela and her family leave the town because of the scandal the event has created.
The narrator mentions several times that the Vicario brothers are good people. They do not kill Santiago in a heated fury; the unfolding of the event takes hours. The town is divided into people who know what is going to occur and feel that the event should be stopped, people who think that the brothers are joking, and authority figures who are lax in their duties and allow the murder to occur. The town's tacit acceptance of honor and gender codes within their society condones the murder.
Class differences influence the course of events in the novel. Santiago's family represents the upper class. They have become affluent while others around them exist in poverty. Santiago's difference, resulting from his beauty and his wealth, makes him an object of suspicion in the town. Poorer residents envy him because of his superior financial status. Young men in the town are jealous of his proficiency with women. But the combination of economic and personal interests surrounding Santiago Nasar is never fully elucidated, making his death an unsolvable puzzle.