What are a few moments of suspense in Agatha Christie's And Then There Were None?

That the characters are being picked off one by one generates much of the story's suspense. We don't know who's committing these brutal murders or why, but the fact that these hideous crimes are being carried out with such clinical efficiency adds considerably to the general level of tension. No one can trust anyone around them; everyone could just as easily be the crazed killer as the next victim.
The suspense reaches a fever pitch when Vera and Philip are the last two guests left standing. By this stage, we've been thrown off the scent to such an extent that we're certain that one of these two simply must be the murderer. The cloying air of mystery and suspense is thickened further by the fact that Vera and Philip are arguably the most likable characters in the story. We can't quite believe that either one is a cold-blooded, psychotic murderer. But it's their very likability that makes us all the more anxious to discover the killer's true identity—and this merely adds to the suspense.

In true Agatha Christie fashion, an air of mystery and suspense pervades And Then There Were None. One suspenseful event in the beginning of the novel occurs when the recording is played. After dinner at the isolated, luxurious mansion, a voice accuses each character in turn of murdering someone and not being punished for it.
After the first two deaths, the remaining characters realize that the set of ten little Indian figurines is missing the first two figures. Not only that, the first two figures died in similar fashion to their deceased housemates: choking (from poison) and oversleeping (overdosing on sleeping pills). This increases the suspense because each character faces the chilling idea that he or she is trapped on an island with a murderer who has carefully planned their death. As each character is eliminated, the tension mounts among those who remain.
The suspenseful climax of the book occurs when the (supposedly) last two characters left alive each believe the other is the killer. Vera grabs Lombard’s gun and kills him, then in turn kills herself with a noose that has been left waiting for her.