In 1933, retired detective Hercule Poirot is targeted by a taunting killer who sends letters signed "ABC", which Poirot must decode in order to discover the identity of the murderer.In 1933, retired detective Hercule Poirot is targeted by a taunting killer who sends letters signed "ABC", which Poirot must decode in order to discover the identity of the murderer.In 1933, retired detective Hercule Poirot is targeted by a taunting killer who sends letters signed "ABC", which Poirot must decode in order to discover the identity of the murderer.