Emily and Vera take a walk together. Emily reiterates her conviction that Mrs. Rogers died of a guilty conscience. She tells Vera the story of Beatrice Taylor, the girl the recorded voice accused Emily of killing. Beatrice Taylor worked for Emily as a maid, but when Beatrice got pregnant, Emily immediately threw her out of the house. Friendless and despairing, Beatrice drowned herself. Emily insists that she has no reason to feel remorse, but the story horrifies Vera.
Meanwhile, Lombard and Armstrong consult with each other. They discuss the possibility that Rogers killed his wife, and Armstrong expresses his conviction that the Rogers couple probably did kill the old woman in their care simply by withholding drugs that she needed. They also consider the possibility that Mrs. Rogers killed herself, but two deaths—hers and Marston’s—within twelve hours seems like an improbable coincidence. Armstrong tells Lombard that two Indian figures have disappeared. When Armstrong recites the first two verses of the poem, Lombard notices that they neatly correspond to the two murders. They decide that their host, Mr. Owen, committed the murders and is now hiding on the island, and they determine to search for him.
Joined by Blore, Armstrong and Lombard make an exhaustive sweep of the small island. Since the island is mostly bare rock, few places for concealment exist. It turns out that Lombard has a revolver, which surprises Blore. As they make their search, the men come across a dazed Macarthur sitting by himself, staring off into the sea. He tells them that there is very little time and that they need to leave him alone. They decide that he must be crazy. Leaving him, they discuss how they might signal the mainland, and Lombard points out that a storm is brewing, which will isolate them. He adds that the fishermen and village people probably have been told (by Mr. Owen, presumably) to disregard all signals from the island. The men come to some cliffs they want to search for caves, but they need a rope. Blore returns to the house to get one, while Armstrong wonders about Macarthur’s apparent madness. Meanwhile, Vera goes out for a walk and comes across the Macarthur. She sits down, and he talks of the impending end of his life and of the relief he feels, given the guilt he has felt over the death of Richmond. Eventually, having seemingly become unaware of Vera’s presence, he begins to murmur the name of his dead wife as if he expects her to appear.
When Blore returns with a rope, he finds only Armstrong, who is musing that Macarthur may be the killer. Lombard returns, having gone to check some unnamed theory, and climbs down the cliff to make his search for caves. As Armstrong and Blore hold the rope, Blore remarks that Lombard climbs extremely well. He says he does not trust Lombard and thinks it odd that he brought a revolver, saying, “It’s only in books that people carry revolvers around as a matter of course.” Lombard finds nothing on the cliff face, and the three men return to the house, where they make a thorough search for their missing host. The search goes quickly, since the modern house contains few potential hiding places. They hear someone moving about upstairs in Mrs. Rogers’s bedroom, where her body has been laid, but it turns out to be Mr. Rogers. Completing their search, they conclude there is no one on the island but the eight of them.
We are finally given an account of Emily Brent’s crime in the form of a remarkably honest confession from her own mouth. She makes an interesting case, since, in a certain way, she is less explicitly guilty of murder than most of the other guests. After all, her only action was to turn a pregnant girl out of her home: she did not intend to kill Beatrice Taylor the way Vera intended to kill Cyril or Macarthur intended to kill Richmond, his wife’s lover. Nor did Emily directly cause someone’s death, as did Armstrong and Marston. Nevertheless, Christie depicts Emily as the most unsympathetic character in the novel, less for what she did than for her utter lack of remorse and unbending faith in her own righteousness. The others may have committed worse crimes, but at least they admit to themselves that they did indeed commit crimes. Emily Brent has no such consciousness of her own guilt. She is, as Christie puts it, “encased in her own armour of virtue,” using her religious values to justify her actions.
Meanwhile, some of the characters begin to realize the truth about the situation and the danger they are all in while they inhabit an island with a crazed murderer. In particular, we see the three younger men—Armstrong, Blore, and Lombard—begin to work together in an effort to solve the mystery. Armstrong and Lombard make the connection between the poem, the deaths, and the missing figurines, which enables them for the first time to grasp the murderer’s overall plan. Then, deciding to search the island, they turn to Blore to provide muscle. This grouping of three seems like a strong alliance, bringing together Armstrong’s intelligence, Lombard’s cunning, and Blore’s police experience. Indeed, these three men end up, along with Vera, the last surviving guests. The murderer appears to be weeding out the weaker characters first: Marston, self-absorbed and overconfident, dies first, followed by the fainting Mrs. Rogers. Macarthur’s increased detachment from the world, manifested in his odd behavior during these chapters, makes him an easy target for the murderer. That the strongest characters survive prepares us for a heightening of events, since the murderer will no doubt have to be savvy to kill them off.