In the short story The Chocolate Box, Paul Déroulard was a promising young French politician. He was a Deputy and slated to become a government minister. He had married a young wife from Brussels who came from a wealthy family. Her money would prove useful to his political career. His wife died about two years after their marriage, after apparently having fallen down the stairs. Among the property which Déroulard inherited from his wife was a house on the Avenue Louise in Brussels. While living in this house, Déroulard himself also died, quite suddenly after dinner, apparently from a heart-failure.
Although his death was attributed to natural causes, Poirot, then a member of the Belgian police, was nonetheless persuaded to investigate the case by Virginie Mesnard, a cousin of the late Mrs Déroulard. Poirot would later consider this investigation to be one of his few failures.
According to Poirot, Paul Déroulard was a peculiar man. He had many scruples and did not smoke or drink. However he had a weakness for women. Déroulard was also a bitter anti-Catholic. Both of these attributes would feature in his fate.