Sir Thomas Legge, Assistant Commissioner of Scotland Yard, and Inspector Maine discuss the murders at Indian Island. Maine notes that the coroner's report identified the causes of death in all ten victims but could offer nothing more. When Legge asks if the townspeople helped to shed any light on the case, Maine informs him that they were no real help. Because of the former owner's outlandish parties, the townspeople were used to strange happenings on the island. In addition, they had been informed by Isaac Morris, acting for U. N. Owen, that an odd bet related to spending a week on a deserted island was taking place. Maine states that nothing further can be uncovered about Owen because Morris did such a clever job of covering his employer's tracks. Maine also comments that Morris too was recently murdered and notes that Morris was likely involved in criminal activities. Main then states that Fred Narracott took his boat to the island after learning that a group of Boy Scouts had seen SOS signals from the island. Narracott did so, despite Morris' comments, because he felt that the people he ferried to the island were a rather "normal" and "quiet", not at all like the former owner's guests. Legge asks if someone could have swum ashore, and Maine replies that the seas were too rough and the distance too great. Legge then inquires about the phonograph record. Maine addresses each of the accused and notes that it is possible some of them were guilty. Legge replies that Owen seems to have wanted to address "cases the law couldn't touch".
When Legge again expresses his amazement at not knowing how or why the crimes occurred, Maine notes that they do know why: someone with a penchant for justice wanted to see justice executed. Maine suggests that Legge may be thinking that if no one was able to escape the island, then the murderer must be one of the guests. He notes that there is some evidence to help them, in the form of diary entries left by Claythorne and Brent, as well as notes taken by Wargrave. This information establishes the order of death of the first six victims: Marston, Mrs. Rogers, Macarthur, Rogers, Brent, and Wargrave. Maine then speculates on the how the remaining four might have died and who could have committed the murders. His ultimate conclusion is that the killer must have been someone other than the ten guests, someone who managed to elude detection and to escape the island.
The Scotland Yard Inspectors' failure to make a solid case for the crimes that occurred on Indian Island reinforces the murderer's contention that there are numerous serious crimes that go beyond the reach of the law. Narracott's observation that the guests were "normal" people reflects the novel's assertion that even the average person can commit murder. Maine's conclusion that the murderer must have been someone other than the guests further enhances the notion that getting away with murder is easy.