It is a "closed circle" murder mystery: the victim is a passenger on a cross-Channel aircraft flight, and the perpetrator can only be one of eleven fellow-passengers and crew.

[2] Hercule Poirot travels back to England on the midday flight from Le Bourget Airfield in Paris to Croydon Airport in London.

The others include mystery writer Daniel Clancy; French archaeologists Armand Dupont and his son Jean; dentist Norman Gale; Doctor Bryant; French moneylender Madame Giselle; businessman James Ryder; Cicely, Countess of Horbury; the Honourable Venetia Kerr; and Jane Grey, a hairdresser.

Clues gradually emerge: the victim had two coffee spoons with her cup and saucer; the blowpipe was bought in Paris by an American man; Lady Horbury is one of Giselle's debtors, and had been cut off from her husband's money; Giselle employed blackmail to ensure that her debtors didn't miss their repayments; only the stewards and Clancy passed by the victim on the flight; Lady Horbury's maid was on the flight after asking to be on it at the last moment.

The murder was carefully planned: Gale had brought his dentist's coat on the flight, which he changed into after some time to pose as a steward, knowing no-one would pay attention to such a person.

Under the guise of delivering a spoon to Giselle, he stabbed her with the dart, then removed his coat and returned to his seat before the body was found.

Anne's murder was part of the plan – Gale married her when he learned she was Giselle's daughter, intending to kill her at a later date in Canada, after she had received her mother's estate, and having ensured that he would in turn inherit the money from her.

The wasp that buzzed around in the rear compartment was released from a matchbox that Gale brought with him; both this and his coat had aroused Poirot's suspicions when he read the list of passengers' possessions.

"[3] The Times in its main paper gave the book a second review in its issue of 2 July 1935 when they described its plot as "ingenious" and commented on the fact that Christie had evolved a method of presenting a crime in a confined space (with reference to The Mystery of the Blue Train and Murder on the Orient Express) which "however often employed, never loses its originality.

Not that such minor matters are of the slightest consequence to the reader; the main thing is that this is an Agatha Christie story, featuring Hercule Poirot, who is, by his own admission, the world's greatest detective.

[5]In The Observer's issue of 30 June 1935, "Torquemada" (Edward Powys Mathers) started his review, "My admiration for Mrs. Christie is such that with each new book of hers I strain every mental nerve to prove that she has failed, at last, to hypnotize me.

Agatha Christie has recently developed two further tricks: one is, as of the juggler who keeps on dropping things, to leave a clue hanging out for several chapters, apparently unremarked by her little detective though seized on by us, and then to tuck it back again as unimportant.

He finished by saying, "Mrs Christie provides a little gallery of thumb-nail sketches of plausible characters; she gives us all the clues and even tells us where to look for them; we ought to find the murderer by reason, but are not likely to succeed except by guesswork.