Convinced that there is no one else on the island, Lombard proclaims that the deaths of Marston and Mrs. Rogers were mere coincidences. Yet Armstrong and Blore insist that the deaths couldn't be suicides or accidents. Blore questions whether Mrs. Rogers' death might have come from an accidental overdose of the medication Armstrong gave her the previous evening. Armstrong becomes livid at the suggestion, but Blore reminds him that, if the recording is right, it's not the first time he made a fatal medical mistake. Lombard notes that there's no use fighting amongst themselves, since they are all in the same situation. Blore remarks that Lombard too has his secrets, again questioning why Lombard brought a revolver to the island. Lombard reveals that he wasn't completely honest with the group yesterday. He notes that he was approached by a man, who offered him a small sum of money to come to the island and observe the other guests. Assuming there might be trouble, he packed the revolver. When Blore asks why he didn't reveal his true position earlier, Lombard states that he thought the deaths of Marston and Mrs. Rogers might be the events he was supposed to observe. However, he now believes that he's in the same situation as the others, and he asserts that Owen is behind it all.
Rogers calls the group to lunch, noting that there is plenty of canned food available. When Brent enters, she proclaims that a storm is coming. Wargrave enters and notes that the others have been very busy this morning. Claythorne also arrives and apologizes for being late. Brent comments that she's not the last arrival; MacArthur has yet to appear. Rogers says that he will go get MacArthur, but Armstrong insists that he will get him. The group begins to eat but soon hears the rapid approach of footsteps. Armstrong enters the room and announces that Macarthur is dead.
As MacArthur's body is retrieved, the storm breaks. Armstrong and Blore take the general's body to his room. Claythorne goes to the dining room table and is soon followed by Rogers. Both recognize that another Indian figurine is missing. When Armstrong and Blore return, Wargrave asks for Armstrong's diagnosis. Armstrong announces that the cause of death was a blow to the back of the head. Upon hearing the news, Wargrave offers his analysis of the situation: Mr. Owen did indeed invite them to the island, and Mr. Owen is on the island. Unfortunately, Mr. Owen is one of them.
Claythorne is horrified, but Wargrave reaffirms that one of them must be the killer. Armstrong and Blore agree, with Blore asserting that he knows the murderer's identity. Wargrave quiets Blore for the moment, pressing the others for their agreement on the issue. Brent and Lombard consent, but Claythorne continues to espouse disbelief. Wargrave proceeds to review the "evidence". He turns to Blore, who suggests that Lombard's possession of a revolver and failure to tell the truth last night points to his guilt. Lombard retells his story, and Blore announces that there's nothing to corroborate Lombard's story; Wargrave then notes that nothing can corroborate any of their stories. When Wargrave asks if there is anyone who can be eliminated, Armstrong asserts that he is a well-known and well-respected man. Wargrave stresses that being respected doesn't make one above suspicion. Lombard suggests that the women should be above suspicion, yet Wargrave gets Armstrong to admit that a woman could have delivered the blow that killed Macarthur. Claythorne lashes out at Wargrave, who notes that he is not accusing her, simply pointing out that all of them are suspects. Wargrave turns to Brent, hoping that she is not offended at the notion. Brent notes that the suggestion is offensive to her but that she can accept the fact that one of them is a killer.
Wargrave suggests that since no one can be eliminated on the basis of character or position, they must concentrate on the facts. He questions whether any of them did not have the opportunity to administer cyanide to Marston, give an overdose of the sleeping medication to Mrs. Rogers, or strike Macarthur in the head. After some vigorous debate, it is determined that any one of them could have killed Marston or Mrs. Rogers. Next, the death of Macarthur is examined. The remaining guests offer accounts of their whereabouts during the morning, and again it is concluded that any of them could have murdered Macarthur. Again, Wargrave asserts that the killer is one of them, and the best thing they can do is to attempt to make contact with the mainland. Wargrave warns each of them to be on guard for his or her safety and to take no risks.
Brent's recognition of the approaching storm is an indication that psychological pressures are continuing to build, and the actual arrival of the storm, coinciding with the discovery of MacArthur's body, suggests that the tension among the guests has finally erupted.
Blore's suggestion that Armstrong may have given Mrs. Rogers an overdose further emphasizes the theme of suspicion, and Armstrong's reaction to the assertion demonstrates that tensions between the guests have reached the boiling point.
Wargrave's review of the "evidence" enhances the theme of judgment, and his careful direction of the discussion is evidence of his carefully crafted plan. Wargrave's comments also establish the fact that anyone, regardless of age, profession, or social status, could be a murderer. His proclamation that the murderer is on the island and is actually one of them is ironic, though the other guests will not uncover the irony.