The suggestion to base the story in ancient Egypt came from noted Egyptologist and family friend Stephen Glanville. He also assisted Christie with details of daily household life in Egypt 4000 years ago. In addition he made forceful suggestions to Christie to change the ending of the book. This she did but regretted the fact afterwards, feeling that her (unpublished) ending was better. The novel is based on real letters translated by egyptologist Battiscombe Gunn, from the Egyptian Middle Kingdom period, written by a man called Heqanakhte to his family, complaining about their behaviour and treatment of his concubine.