Paul Déroulard is the main antagonist of Agatha Christie's short story, The Chocolate Box. Initially, he is presented as the story's victim, but much of his depraved nature was later revealed. He was also revealed to be a murderer, who killed his own wife, and it became the factor to his murder.
He is portrayed by James Coombes.
Paul Déroulard, a French Deputy who was living in Brussels, had died from heart failure. At a time of strife over the separation of church and state M. Déroulard was a key player as an anti-Catholic and a potential minister. He lived in a Brussels home that his late wife left him. He had a reputation as a ladies' man. Mademoiselle Virginie Mesnard, a cousin of his late wife, asks Poirot to investigate. She is convinced that his death three days earlier was not natural. M. Déroulard's household consists of four servants, his aged and infirm aristocratic mother, herself, and on that night, two visitors: M. de Saint Alard, a neighbour from France, and John Wilson, an English friend.
Virginie introduces Poirot into the household and he begins interviewing the servants about the meal served on the night of M. Déroulard's death. He suspects poison, but all ate from common serving dishes. In the study where the death occurred, Poirot spots an open but full and untouched box of chocolates. M. Déroulard ate some chocolates every night after dinner, finishing a box on the night of his death. The servant retrieves the empty box. Poirot notices that the lids of the two boxes, one blue and one pink, are switched. As only Déroulard ate the chocolates, the new box should not have been opened yet. His doctor says Saint Alard and Déroulard had argued strenuously that evening, justifying the cause of death. Poirot finds the local chemist who made eye drops for the aged Madame Déroulard, for her cataracts. He finds the "English chemist" who had made up the prescription of trinitrin for John Wilson, small tablets in chocolate to lower blood pressure. Too many tablets at once would prove fatal. This development bothers Poirot. Wilson had the opportunity but not the motive whereas the position is reversed for M. de Saint Alard. Virginie gives Poirot the address of Saint Alard in the Ardennes. In the disguise of a plumber, Poirot breaks into the house and discovers an empty pill bottle from Wilson in the bathroom cupboard. Poirot thinks he has solved the case.
In Brussels, Madame Déroulard summons Poirot. Learning that Poirot was a police officer who had concluded his investigations, she confesses to the murder of her son. Some years before, she saw him push his wife down the stairs and realised “He was an evil man.” Afraid of the persecution that her son’s new role would bring upon the church and for his approaches to the innocent Virginie, she resolved to kill her son. She stole John Wilson's tablets. She opened the new box of chocolates before seeing that the previous box was not yet empty. After inserting about 20 tiny tablets in one chocolate, she took the opportunity to place the empty bottle into M. de Saint Alard's pocket when he came to say his farewell, thinking that his valet would throw it away. Poirot told her that he had completed his investigation and the matter was closed.
Madame Déroulard died a week later of her infirmities. Poirot considers his mistakes. The mother’s poor eyesight would cause her, and only her, to swap the lids. He misread the psychology of a murderer - Saint Alard would never have kept the empty bottle had he been guilty. Poirot told Hastings to remind him with the phrase chocolate box, if he seemed conceited. Then, he unconsciously goes on to boast about his successes. Hastings hesitates, considers, then graciously refrained from comment.
- Like Grace Springer, Mrs. Clapperton, Henry Reedburn, Harrington Pace, Sir Reuben Astwell, Paul Renauld, Simeon Lee, Lady Boynton, Leslie Ferrier, Samuel Ratchett, Mary Gerard, Lord Edgware, Madame Giselle and Stephen Norton, Paul is presented as a murder victim, but their depraved nature and/or former crimes soon come to light in some parts of the stories.
- According to Poirot in The Chocolate Box and according to Hastings in Peril at the End House, Poirot had never forgive himself due to his mistake at the murder case of Paul Déroulard. It was also considered by Poirot himself as his greatest failure of all time, to the point of he was ashamed of it for his entire life, even after he successfully discovered the truth.
- Like Samuel Ratchett, Paul is an interesting case in Poirot stories, since he was both a victim and a murderer, yet served as the sole villains in their respective stories for the people who killed them were actually sympathetic.