In The ABC Murders, Poirot receives as a warning letter, because none of these villains can just do their murders, they have to tell the world-famous detective first. The mysterious ABC writes a taunting letter threatening the murder, and then kills Alice Ascher of Andover, leaving a railroad timetable (called an ABC guide) at the scene. 

The whole concept of the ABC murders seems more like something the Joker would pull in Gotham City than an Agatha Christie mystery.  But somehow the taunting letters feel ominous, not goofy, and it's scarier  than her other mysteries because the randomness feels like a serial killer  all over the country, not an inheritance drama in a country house. 

Hercule Poirot, with his little grey cells and loyal pal Hastings, pieces together clues...

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