The following version of the novel was used to create this study guide: Christie, Agatha. Crooked House. William Morrow Paperbacks, February 10, 2010. Kindle.

In the novel Crooked House by Agatha Christie, one member of the Leonides family inherited all of the clan's worst traits. Yet, it was hard for the family to believe that one of its own was so morally bankrupt that they murdered Aristide Leonides, the elderly patriarch. Leonides' wife (Brenda) and her lover (Laurence Brown) were arrested for the murder. However, there was doubt that the real murderer had been caught. Although evidence pointed in their direction, no one seemed to believe Brenda and Laurence were the real killers. The family was stymied with its own doubts because if Brenda and Laurence were innocent, then one of their own had committed the crime.

When Charles Hayward decided he wanted to marry Sophia Leonides, he knew little about her except that she had told him that she and her extended family “all lived together in a little crooked house” (4). Charles and Sophia made no serious plans. Then, two years later they were reunited in London. It was at this point that Charles had the opportunity to get to know Sophia’s family because he was investigating the murder of her grandfather.

Aristide had been poisoned with his eye drops, a substance all members of the family knew was lethal if taken internally. Someone had emptied an insulin bottle and refilled it with the eye drops. The investigation into the murder did not go well since there was not really much condemning evidence against any family member who knew about the eye drops. Though Brenda, Aristide’s young wife, gave him his injection before he died, Brenda said that she was innocent. There seemed to be no reason that others in the family would want him dead.

During the course of his investigation, Charles met Josephine, Sophia’s younger sister who claimed to be working on solving the murder on her own. She said she knew who killed Aristide, but she refused to give the name to Charles. Josephine said the police were too stupid for her to help them. She mentioned that it was about time for another murder. Hours later, Josephine was badly injured when a doorstop fell on her, what police believed was a booby trap the real killer had prepared in an attempt to silence the child. Information that Josephine had given Charles during a discussion the day she was injured led him to a pack of love letters that Brenda had written to Laurence. The letters were seen as evidence that Brenda and Laurence had a motive to kill Aristide. They were arrested.

An odd uneasiness was in the air at Three Gables because all of the members of the Leonides family did not really seem to believe that Brenda and Laurence were the real killers. When Nannie was poisoned after drinking Josephine’s left over cocoa, their fears were realized, the murderer was still among them. The day of Nannie’s death, Edith, Josephine’s elderly aunt, took her for a drive. She said she believed Josephine needed to be away from the house with a second murder investigation taking place. News came back hours later that Edith had wrecked her car in a quarry. Both she and Josephine were dead.

Edith left behind two letters. One was to the police commissioner. It contained Edith’s confession, that she had been the one to kill Aristide and Nannie. She commented only that she did not want two innocent people to go to jail. In a letter solely for Charles, Edith further elaborated she had found a notebook in which Josephine wrote regularly. In this notebook, Edith found proof that it was Josephine who had committed the murders, something she had suspected all along. Edith explained she had killed Josephine because she loved her and did not want her to suffer for her crimes as she would in the earthly justice system. When Charles later admitted to his father, the assistant police commissioner, that it was Josephine who had committed the murders, his father was not surprised. He had suspected so for some time.