And Then There Were None is one of Agatha Christie's best-known mysteries. Writing for The Times Literary Supplement of 11 November 1939, Maurice Percy Ashley stated, "If her latest story has scarcely any detection in it there is no scarcity of murders." He continued, "There is a certain feeling of monotony inescapable in the regularity of the deaths which is better suited to a serialized newspaper story than a full-length novel. Yet there is an ingenious problem to solve in naming the murderer. It will be an extremely astute reader who guesses correctly." Many other reviews were as complimentary; in The New York Times Book Review of 25 February 1940, Isaac Anderson detailed the set-up of the plot up to the point where 'the voice' accuses the ten people of their past misdemeanors and then said, "When you read what happens after that you will not believe it, but you will keep on reading, and as one incredible event is followed by another even more incredible you will still keep on reading. The whole thing is utterly impossible and utterly fascinating. It is the most baffling mystery that Agatha Christie has ever written, and if any other writer has ever surpassed it for sheer puzzlement the name escapes our memory. We are referring, of course, to mysteries that have logical explanations, as this one has. It is a tall story, to be sure, but it could have happened."
Dreams and hallucinations recur throughout the novel, usually as a reflection of various characters’ guilty consciences. Dr. Armstrong has a dream in which he operates on a person whose face is first Emily Brent’s and then Tony Marston’s. This dream likely grows out of Armstrong’s memories of accidentally killing a woman on the operating table. Emily Brent seems to go into a trance while writing in her diary; she wakes from it to find the words “The murderer’s name is Beatrice Taylor” scrawled across the page. Beatrice Taylor is the name of Emily Brent’s former maid, who got pregnant and killed herself after Emily Brent fired her. Brent’s unconscious scrawl demonstrates, if not her guilty conscience, at least her preoccupation with the death of her servant. Vera Claythorne often feels that Hugo Hamilton—her former lover, for whose sake she let a little boy drown—watches her, and whenever she smells the sea, she remembers the day the boy died, as if hallucinating.