Appointment with Death
Mrs. Boynton was a dominating tyrant. All her family members were not allowed to talk to people in the “outside” world, even on their first vacation in their lives.
Her stepson, Lennox Boynton was totally helpless and his wife, Nadine, wanted to move out and live their own lives. Meanwhile, Nadine’s friend, Jefferson Cope was in love with Nadine and wished to make her happy. Raymond and Carol Boynton wanted freedom from their stepmother’s claws. Raymond was smitten by the attractive doctor, Sarah King, who told off Mrs. Boynton. Ginevra Boynton, also known as Jinny, told Dr Theodore Gernard that she was a captive in the family.
Then, suddenly, Mrs. Boynton passed away not peacefully from her heart problem but murdered with a fatal injection. Besides the suspects above, Lady Westholme and Amabel Pierce were also involved in the case, telling Hercule Poirot their story.
Just like Murder in Mesopotamia, the key to the mystery is totally psychological.
One comment about this mystery is that it is a bit longwinded, but this is necessary for the readers to understand the personalities of the characters.