Death in the Clouds // Death in the Air — Agatha Christie

It was a most extraordinary case. A woman murdered with the venom-dipped dart of a South African blow-gun on a routine flight over the English Channel. More bizarre still: that the killing could go completely unnoticed by the plane's other passengers. And most ironic of all: that Hercule Poirot, the brilliant detective, should be sitting not fifteen feet from the victim!