Quick recap
Carla Lemarchant asks Poirot to look into a 16-year-old case. Her mother, Caroline Crale, was convicted of poisoning her husband, painter Amyas Crale, and died in prison. Before she died, she left her daughter a letter swearing she was innocent. Poirot has no physical evidence, only five witnesses from back then: brothers Philip and Meredith Blake, model Elsa Greer, the governess and Caroline's younger sister, Angela. He asks each to write down what they remember. Comparing their accounts, Poirot finds the killer was Elsa, the painter's lover, once she learned he wouldn't leave his wife. Caroline took the blame because she believed Angela had done it.
No spoilersOpens once you mark the title as seen.