Sunday morning, Meursault, Marie, and Raymond set out for the beach as planned. Meursault notes that he testified at the police station the day before that Raymond's mistress had cheated on him. On the way to the bus stop, they see a group of Arabs "staring at us…in that way of theirs, as if we were nothing but stones or dead trees." Raymond tells Meursault that one of the Arabs is his mistress' brother and grows worried. They continue to the bus stop and observe that the Arabs neither watch them nor follow them.
Raymond is afraid and convinced he's being followed, but it's entirely unclear whether or not the group of Arabs even notices Raymond. They may be living their lives without regard to Raymond, simply looking at whomever passes by.
They ride to the outskirts of Algiers where Raymond's friend, Masson, has a bungalow with the Parisienne, his wife. Marie and the Parisienne laugh together and Meursault "for the first time…really thought I was going to get married." Masson, Meursault, and Marie go out to swim. Swimming alone with Marie, Meursault reflects that "we felt a closeness as we moved in unison and were happy." After Masson goes in, they have sex in the water.
Meursault may not feel any spiritual or emotional attachment to Marie, but his physical bond with her is unwaveringly strong. Though the idea of love has no effect on Meursault, the sound of Marie's laugh convinces him they are "really" marrying. They bond physically (through swimming and sex) rather than through conversation.
After a wine-heavy lunch, Meursault, Raymond, and Masson take a walk on the beach. In the midday heat, "the glare on the water was unbearable." Meursault reflects, "I wasn't thinking about anything, because I was half asleep from the sun beating down on my bare head." They see two Arab men approaching from the far end of the beach. Raymond tells them one of the men is his mistress' brother and, still walking steadily, tells them he'll "take care of my man" if there's trouble. He tells Masson to handle the other man and Meursault to handle anyone else who shows up. Meursault observes "the blazing sand looked red to me now."
The crushing heat again evokes the world's utter indifference for human comfort, beating down on Meursault's head so forcefully it stops his thoughts. The glare on the water asserts the primacy of physical experience so powerfully that it's painful to witness it. The blood-colored sand foretells violence.
When the two groups meet, the Arab men stop walking and Raymond goes up to the one he recognizes and says something that Meursault can't make out. Raymond strikes the man. Masson strikes the other Arab man, who falls facedown in the water and lies still. Raymond's target is also on the ground and, just as Raymond prepares to "let him have it," the man slashes Raymond's arm and mouth with a knife. The two Arab men back off holding the knife before them. Then they run off. The men return to the beach house. The women are upset and frightened.
Raymond initiates the fight all on his own, saying the first words and striking the first hit. Though the words are inaudible, they are presumably insulting or combative. The Arab man slashes Raymond in defense.
After being bandaged, Raymond insists on going back down to the beach, carrying a concealed gun. Meursault follows. They walk in silence to the far end of the beach where they find the two Arab men lying by a spring, one playing a reed flute. The two lie calmly watching. Raymond reaches for a gun but Meursault insists Raymond can't shoot unless he is attacked with a weapon, convincing Raymond to give him his gun and "take [the Arab] man on man." All stand still in "the double silence of the flute and the water." Meursault notes, "it was then I realized that you could either shoot or not shoot." The Arabs back away, and Raymond feels better. He and Meursault head back towards the bungalow.
Meursault, level-headed in contrast to Raymond's reckless passion, keeps Raymond from acting rashly. Meursault's realization ("that you could either shoot or not shoot") evokes the famous line (and philosophical crisis) of Shakespeare's Hamlet: "to be or not to be." Meursault is saying: you could kill or not kill. Hamlet is saying: you could kill yourself or not kill yourself. Raymond is, as usual, protective of his image and only feels better once the Arab men have physically conveyed surrender by backing away.
Raymond climbs the steps up off the beach and goes back to the bungalow. Meursault, though, stands at the base of the steps, head ringing in the intense heat, and feels "unable to face the effort" of climbing up and seeing the women again. He thinks, "to stay or to go, it amounted to the same thing." He walks back down the beach hoping to see the spring again and rest in its shade. "There was the same dazzling red glare" on the beach and each flash of the sun's reflection is described as "a blade of light."
Heat and the world's brutal indifference continue to overpower Meursault's sense of the world. This relatively harmless glare and "blade of light" foreshadows a fatal blade of light soon to come.
At the spring, Meursault is "a little surprised" to see that the Arab man who is Raymond's enemy has returned and thinks, "as far as I was concerned, the whole thing was over, and I'd gone there without even thinking about it." To Meursault's eyes in the blazing sun, the Arab "was just a form shimmering…in the fiery air." Meursault notes the light is the same as it had been on the first walk and thinks, "for two hours the day had stood still." He likens the heat to the heat on the day of his mother's funeral and reflects that "it was this burning, which I couldn't stand anymore, that made me move forward."
Though Meursault may feel "the whole thing was over," the fight actually happened only a little while earlier and must surely be fresh in the Arab man's mind. Shimmer obscures the Arab man, making him look like "just a form," not a full human being. Likening the day to the day of the funeral summons death into the scene right before Meursault shoots. It is heat – or the world's indifference – that makes the usually passive Meursault take action and shoot.
The Arab man draws his knife and the sun reflects off it in a "dazzling spear…[that] stabbed at my stinging eyes." Reeling in the heat, Meursault "squeezed" the revolver and "the trigger gave." He reflects, that that "is where it all started…I knew that I had shattered…the exceptional silence of a beach where I'd been happy." He fires four more shots at "the motionless body…and it was like knocking four quick times on the door of unhappiness."
Meursault shoots in response to the dazzling spear that stabs him, but that spear isn't the Arab's blade itself – it's only the sun's reflection flashing off that blade. Meursault feels he's shooting that dazzle, but ends up killing the Arab. The "it" that "started" is crucially unspecified. Is it unhappiness? The end of silence?