Warning: Wikipedia contains spoilers.
In the ABC murders an apparent serial killer is murdering people in order of their names: first Annabel Ascher of Andover, second Betty Barnard of Bexhill, third Sir Carmichael Clarke of Churston, and so on. A man by the name of Alexander Bonaparte Cust is arrested for the murderers, but Poirot deduces that the murders were committed in order to hide one specific murder.
wikipedia.org dumped 2003-03-17 with terodump