Following breakfast, Brent convinces Claythorne to accompany her to the island's summit to watch for the boat. The two women discuss Mrs. Rogers' death, with Brent stating she is certain Mr. Rogers killed his wife. When Claythorne notes how forlorn Mrs. Rogers seemed, Brent quotes: "Be sure thy sin will find thee out". Claythorne remarks that if the letter's accusation is true about Mr. and Mrs. Rogers, this implies it is also true of the others. Brent notes that Lombard admitted he passively killed the natives, but, she suggests, Wargrave was only performing his civic duty and Blore's accusation doesn't seem valid. Of course, she asserts, the accusation against her isn't true either.
Brent describes the events surrounding the death of Beatrice Taylor, a servant she employed. According to Brent, Taylor was a woman of "loose morals" who became pregnant out of wedlock. Brent fired her, and the woman committed suicide. When Claythorne asks Brent if she felt any remorse over the young woman's death, Brent notes that she had no sense of guilt.
Armstrong and Lombard discuss the recent events. When Armstrong asks if Lombard believes Mr. Rogers killed his wife, Lombard notes that it makes sense as an isolated event. When Lombard asks Armstrong if he believes that Mr. and Mrs. Rogers poisoned Miss Brady, Armstrong notes that Mr. Rogers revealed that Brady had a specific heart condition. As such, Mr. and Mrs. Rogers may have killed her by simply withholding her medication. Armstrong suggests that it would have been almost impossible to prove their guilt. Lombard then notes that there is an important similarity between Brady's death and Edward Seton's death. In both cases, the killer was able to craftily conceal the murder. Ironically, Lombard observes, the fact that Marston and Mrs. Rogers died on the island allows their deaths to be hidden. This revelation forces Armstrong to consider his own situation: he had been able to avoid punishment for the death of his patient because it had occurred in a hospital. The pair continue to discuss the two recent deaths, and the conclusion, drawn by both men but only voiced by Lombard is that both Marston and Mrs. Rogers were murdered.
As they continue to talk, Armstrong mentions the two missing figurines, which causes Lombard to recite the first few lines of the poem. He immediately recognizes that the deaths in the poem mimic Marston's and Mrs. Rogers' deaths. He also connects the poem to their host, Mr. Owen. When Armstrong reminds Lombard that Rogers swore there was no one else on the island, Lombard suggests that Rogers is either wrong or lying; he then suggests that all of the events are part of a carefully constructed plan, designed by Owen. When Armstrong remarks that Owen must be a madman, Lombard states that the one thing Owen may have overlooked is that the island is very small. As such, they may be able to locate him. Armstrong remarks that Owen may be dangerous. Lombard dismisses the assertion but suggests that they should enlist the help of Blore.
Brent's use of the passage "Be sure thy sin will find thee out" is further evidence of her guilty conscience. Her comments about the validity of the accusations leveled against Lombard, Wargrave and Blore reveal the complex nature of crime; specifically, guilt and innocence are not necessarily black and white issues. For any crime, even murder, there can be mitigating circumstances. Brent's unsympathetic recounting of Taylor's death implies that some people deserve to die.
Blore and Armstrong's discussion of Miss Brady's death reinforces the theme of concealment. In particular, location as a method of concealment is offered. Their deduction that Marston was murdered is the first recognition of the gravity of their situation, and their linking of the poem to the first two deaths is further evidence of the elaborate plot that has been devised for the guests.
Finally, Lombard's suggestion that they enlist the help of Blore is the first indication of an alliance being formed.