The story was made into a movie in 1990, Poirot being played by David Suchet.
Poirot's vacation in Cornwall takes a sinister turn when the charming Nick Buckley meets him and casually mentions that she's narrowly escaped death three times in as many days. Poirot is not so sure about the presumed accidents and has his worries confirmed when Nick's cousin Maggie is shot dead while getting a coat
After many questionings and examinations, Poirot discovers that the killer is actually Nick herself and that the attempts on her life was staged. The murder of Maggie was not a mistake, but part of a scheme bearing the most common motive of all... money.