Mrs. McGinty's Dead by Agatha Christie

Hercule Poirot had always believed that the solution of a murder lay in an examination of the personality of the victim. That is until he undertook to find out who had murdered Mrs. McGinty. Superintendent Spence came to get Poirot's help because he did not believe that the man convicted of murdering Mrs. McGinty was really guilty. Spence was the policeman who found the evidence on which her boarder, shy, retiring James Bentley, had been accused of the crime, and yet something seemed wrong about the conviction.

Hercule Poirot agreed to investigate, and went to the village of Broadhinny where he found absolutely miserable lodgings at a guest house. It seemed that Mrs. McGinty lead a dull and uneventful life. She cleaned houses and went to church, but she had no friends. She had rented out a room to Bentley after her husband's death. She had left a small amount of money to her niece, Bessy Burch, which really did not justify murder. Poirot could find no motive whatsoever in Mrs. McGinty's life for anyone to kill her.

Then Poirot found that Mrs. McGinty had purchased a bottle of ink. This seemed like such a small fact, but it signified that Mrs. McGinty, who never wrote to anybody, had suddenly found a reason to write. Next, Poirot found a newspaper article which she had read which was about 4 notorious crimes which had been committed in the past along with pictures of the women who had committed them. Could Mrs. McGinty have found one of these women while she was snooping in the houses of those people for whom she cleaned? Poirot then attempted to meet Mrs. McGinty's clients and this paid off when when he finally discovered the identity of the murderer.

Along the way, Ariadne Oliver, a detective story writer entered the story. She was in Broadhinny where the young playwrite, Robin Upchurch, was adapting one of her mystery novels into a play. Ariadne had some choice and humorous comments on mystery writing and on the adaption of books into plays. This book was published in 1952, and there is a David Suchet Poirot episode ( Season 11, episode 1).