Lombard says that they must have been wrong – the deaths were just coincidences. Blore asks Armstrong whether he may have accidentally overdosed Mrs. Rogers on a sleeping pill. Armstrong says that this is ridiculous and Lombard says that they should stop accusing each other.
Lombard, with his logical mind, does not want to believe that one of the guests could be the murderer, or that their comprehensive search could have failed.
Blore then turns on Lombard and asks why he brought a revolver on a social visit. Lombard says that he “expected to run into a spot of trouble” on the trip. He explains that he was asked to come here by a man named Morris who offered him 100 guineas to keep his eyes open. Lombard explains that he didn't say anything last night because he thought the event was exactly the thing he was supposed to cope with. But now Lombard believes he is in the same sticky situation as everyone else – Mr. Morris was lying to him and they are all in a trap.
After having unsuccessfully worked together all day to look for the criminal the men start accusing each other. Society is starting to break down. Blore is understandably skeptical of Lombard's weapon, but Lombard assures him that they are all in the same boat. Although he doesn't want to believe the murderer is one of the guests, he does believe that they are in some sort of trap.
The lunch bell rings and Rogers apologizes that he is only serving cold ham and cold tongue along with other things he could find in the pantry. Lombard asks whether they have enough food and Rogers responds that they have more than enough.
Rogers is trying to keep up the civilized order but he cannot fully succeed any longer as suspicions grow among the guests. At the same time the UNKNOWN host has provided enough food—he wants to punish them directly, not by starving them.
Miss Brent comes in and says it looks like a storm is coming. Vera apologizes for coming in late, but Miss Brent responds that General Macarthur still has not come. Armstrong volunteers to go get Macarthur when Vera says he is sitting by the sea.
The approaching storm mirrors the growing fear among the guests. The social rules are deeply ingrained in all the guests; in spite of their fear they still show up to lunch on time.
After everyone has been eating for a bit Armstrong comes running and shouts that General Macarthur is—and Vera finishes his sentence—“Dead!”
Vera expected Macarthur would be dead because he said he was ready to die.
As the men come back in with Macarthur's body, the storm breaks. Vera goes into the dining room, followed soon after by Rogers. They are both checking the soldier boys and now there are only 7.
This third death makes it clear that the other two were not mistakes, and the breaking of the storm heightens the power of this realization. `
Armstrong says that Macarthur was killed by being hit with a life preserver. Wargrave now takes over the conversation. Wargrave says that he has been sitting all morning thinking over the situation and decided that the two deaths yesterday were not accidental or suicides. Wargrave has therefore concluded that Mr. Owen is on the island. He is one of the guests!
Wargrave asserts what everyone has been suspecting. That Mr. Owen is one of them. By making this statement to the whole group, unlike others who have been making it in individual conversations, he puts himself in a position of power just as he did after the first recorded accusation.
Vera is shocked but Miss Brent believes that Wargrave's theory is true: one of them is possessed by the devil. Blore blurts out that Lombard has a revolver and Lombard explains why he does. Lombard then says that the women must not be suspects but Wargrave responds that either of them would have been physically capable of the murders.
Wargrave says that there can be no exceptions based on “character, position, or probability” they must look at the facts. They agree that anyone could have drugged Marston but Armstrong or Mr. Rogers are most likely to have killed Mrs. Rogers. But then Wargrave states that really anyone had the chance to do it.
There are no real clues left; the only thing they know is that the murderer could be any of the guests. No one has an alibi that puts them above suspicion.
Because they cannot figure anything out from the first two murders, Wargrave decides to move on to the third. They go through each of their alibis. Everyone has a fairly weak alibi, but no one seems to stand out as the killer. They then call in Rogers and he doesn't have much to add either.
Wargrave takes charge as judge as he did after the accusation. He does not exclude himself but does seem to place himself above the others by serving as the arbiter of justice.
Wargrave gives his final summation in which he says that no one person stands out as the criminal. Yet he remains positive that the killer is on the island. He tells everyone to keep their guard up, take no risks and be alert to dangers.
This statement makes survival the one important concern for the guests on the island. They are starting to revert to a primitive state in spite of the comfortable surroundings.