Wargrave's body is carried to his bed, and the group reconvenes in the kitchen. Blore wonders who the next victim will be. Armstrong asks how the murder was possible, and Lombard suggests that the seaweed was a ploy to cause confusion and to draw them to Claythorne's room.
When Blore asks why they didn't hear the shot, Lombard notes that Claythorne's screams coupled with their noisy attempt to reach her and the noise from the storm would easily muffle the sound. Armstrong suggests that although there are four guests left, no one knows the murderer's identity, yet each remaining guest believes he or she knows the murderer's identity. Claythorne announces that she doesn't feel well and states that she is going to bed. The men also agree to turn in. Alone in their rooms, each guest reflects on the situation.
Lombard admits to himself that he's very rattled. To his surprise, when he opens his nightstand drawer he finds the missing revolver.
Claythorne too is very shaken by the recent events. She attempts to calm herself, considering that if she's safe in her room she might just remain there until help finds her. Her mind wanders back to the events surrounding Cyril's death. Though she hid it well, she actually encouraged Cyril to swim to the rock, which ultimately resulted to his death. She recalls how Hugo, her lover, rejected her after Cyril's death. She notices a large black hook in her ceiling, but she doesn't recall it being there before.
Blore ponders Wargrave's death. He believes that someone else will die very soon, but he is sure that it won't be himself. He wonders what has become of the revolver. He lies, fully clothed, on his bed, and as his candle burns down he begins to become unnerved. He mentally reviews the faces of the dead guests and is surprised when an unfamiliar image comes to mind: Landor. He recalls how Landor had a wife and a daughter, and he wonders what became of them. As the clock strikes one o'clock, Blore's attention is drawn to a faint sound outside of his room. As he strains to listen, he realizes that it's the sound of footsteps. The sound unnerves him, but a part of him wants to investigate it. Without much thought, he grabs a lamp for a weapon, carefully opens his door, and moves into the hall, where he glimpses a figure leaving through the front door. He nearly follows the figure outside, but considers that it might be a trap. Blore concludes that he can now positively identify the murderer by figuring out who is not in his or her room. He knocks on Armstrong's door but receives no reply. When he knocks on Lombard's door, he receives an immediately reply and tells Lombard that he believes Armstrong is out of his room. He then knocks on Claythorne's door. When Claythorne inquires who it is, Blore tells her that he will return in a moment. As he returns to Lombard's room, Lombard enters the hallway and Blore explains the events. Lombard verifies Blore's claim by knocking on Armstrong's door. When he too receives no answer, Lombard concludes that Armstrong is the murderer. Lombard peers into the keyhole of Armstrong's room and notes that the key is not in the lock; he concludes that Armstrong must have locked the door from the outside and taken the key with him. Lombard proclaims that they will catch Armstrong; he then races to Claythorne's door, calls to her, and tells her that he and Blore are "hunting" Armstrong. She is to remain in her room, and under no circumstances is she to open the door until both Blore and himself return. When Claythorne agrees, Blore and Lombard rush downstairs. Blore notes that they have to be careful because it is likely that Armstrong has the revolver. This prompts Lombard to reveal that he has the revolver. Blore is frightened by the revelation, but Lombard explains that it simply reappeared in his nightstand drawer and notes that if Blore thinks he intends to harm him, Blore can remain in the house. Blore decides to accompany Lombard.
Claythorne decides to get dressed. She marvels at the cunning method Armstrong has apparently adopted; she then considers how he might fool her into opening her door. She approaches her window and notes that, if necessary, she could leap from it to the ground. She attempts to write in her diary, but her attention is drawn to the sound of breaking glass somewhere downstairs. She thinks she hears the sound of footsteps outside her room, but she dismisses the thought when she hears other, louder sounds of people moving around downstairs. Eventually, Lombard calls her name. She also hears Blore, who asks if she will let them into her room. When she opens the door, Blore and Lombard proclaim that Armstrong has disappeared.
Claythorne can't believe the assertion, but Blore stresses that the entire island has been searched. Lombard also notes that a pane of glass was broken in the dining room, and one of the four remaining figurines was taken.
The mental breakdown of the remaining guests is evident. The seclusion of each guest in his or her room symbolizes the isolation they are experiencing.
The fact that Lombard knocks on Armstrong's door to test Blore's claim that Armstrong is missing further enhances the theme of suspicion. Claythorne's consideration of the possible tricks Armstrong might use to persuade her to leave her room is evidence of her increased paranoia.
Blore's decision to accompany Lombard in a search for Armstrong, even though Lombard reveals that he again has the revolver, can be seen as an instance of trust. Of course, Blore may simply feel he will be safer if he accompanies Lombard.