Claythorne and Lombard have a private discussion, with Claythorne asking Lombard whom he believes the murderer is. Lombard suggests that since she's asking him, she must not consider him to be the murderer. He then states that he believes it is Wargrave, a man who, as a judge, is used to power and holding someone's fate in his hands. Claythorne reveals that she believes Armstrong to be the murderer, since a doctor would have access to poisons and would be credible enough to cover up Macarthur's time of death if he needed to. Lombard suggests that she may be right.
In another part of the house, Blore and Rogers discuss the same issue. Blore states that he has an idea who the murderer may be, asserting that the person must be a "very cool customer". Rogers confesses that he has no idea of the murderer's identity, and that this really bothers him.
Armstrong and Wargrave also discuss the situation, with Armstrong noting that they must get off the island. Wargrave comments that escape isn't likely as long as the winds remain strong. Armstrong stresses that if they do nothing they may all be murdered in bed, but Wargrave dismisses the notion, asserting that they have some advantage because they are all anticipating another murder. When Armstrong suggests that they have no idea who the murderer might be, Wargrave notes that while he has no direct evidence, the signs all point to one person.
Alone in her room, Brent takes out a diary and writes about the recent events. She admits that she is convinced Macarthur was murdered and that the murderer is one of the others. She becomes drowsy as she writes a final line in the entry, claiming that she alone knows the murderer's identity: Beatrice Taylor. As she reawakens and sees the last line, she wonders if she wrote it and if she might be going mad.
The storm grows stronger and the remaining guests gather in the living room. Rogers brings tea and draws the curtains. For a moment the group relaxes. Rogers returns and seems upset; he notes that the bathroom curtain is missing. Blore inquires about the type of curtain and notes that removing a single curtain is mad, though the entire situation in which they find themselves is mad, too. Blore tells Rogers to forget about it. The sense of fear has returned, and the remaining guests look at each other with suspicion.
The guests have dinner and at nine o'clock Brent announces that she is going to bed. Claythorne too states that she will adjourn. Blore follows the two women upstairs and hears them both bolt their doors. When Blore returns, Lombard suggests that at least the women will be safe for the night.
An hour later, the remaining four men go to bed. The judge reminds them to lock their doors, and Blore adds that they should place a chair under the door handle. Rogers remains downstairs and sets the table for breakfast. To ensure that no one tampers with the remaining figurines, Rogers locks the doors to the pantry and the hallway, then places the key in his pocket. He turns out the lights, retires to his room, and checks the only possible hiding place: the wardrobe.
The guests' private conversations suggest other possible alliances, yet these alliances will never come to fruition.
Lombard's suggestion that Wargrave is the murderer is an astute observation, but it is also ironic, since Lombard will not live to actually prove the claim. The guests' private discussions, including Claythorne and Lombard's discussion of Wargrave and Armstrong as the potential murderer and Blore and Rogers' similar discussion, reveal the deepening sense of mistrust among the guests.
Brent's diary entry is evidence of her deep sense of guilt and conscience, and her failure to remember that she actually wrote the entry illustrates the tremendous stress each guest is experiencing.
Wargrave's comment that all of the signs point to the murder is ironic and connects with the comment he offered in the previous chapter about the murderer being one of them.