Agatha Christie's mystery novel The A.B.C. Murders, published in 1936, is an early example of serial killer fiction. Her renowned Belgian detective, Hercule Poirot, is alerted by anonymous letter to a murder that is soon to be committed. Three murders are committed in alphabetical order, each with a letter alerting Poirot ahead of time: a woman with the initials A. A. in the town of Andover, a woman with the initials B. B. in the town of Bexhill, and a man with the initials C. C. in the village of Churston. With each body, the killer leaves an ABC railway guide.

A fourth murder in Doncaster fails to follow the alphabetical theme. The letters to Poirot prove an important clue, as they indicate that the killer wanted him (rather than the police) to investigate. They also prove that the killer wanted to control the timing of the investigation. A false suspect, a stocking salesman who was used by the true killer as a pawn, is arrested but proven innocent due to an alibi for one of the killings. Special paper and a typewriter, along with the ABC guides themselves, also serve as evidence that first implicates the pawn and eventually the real killer. Have fun tracing the clues and trying to solve the mystery alongside Poirot!