In 1976 the last Agatha Christie mystery was published: the Sleeping Murder.
Posthumously published in October 1976 by Collins Crime Club in the UK and Dodd Mead and Company in the US, the Sleeping Murder starred a popular Christie lead, Miss Marple. Christie had died in January 1976 at age 86.
Set in the 1930s until WWII, Miss Marple meets a newlywed Gwenda Reed, who has come to England ahead of her husband to find a home. She purchases Hillside, and during renovations feels like she has been in the home previously.
Reed tells Miss Marple about her history, and that she had lived away from England in New Zealand, and that she believes she has a connection to the house.
When her husband Giles arrives from New Zealand, the duo work with Miss Marple to uncover the truth of her early years and disturbing memories that are resurfacing in Gwenda’s mind as an adult.
Miss Marple discovers the young Gwenda had come back to England and that there is nefarious things going on about her past and the disappearance of her stepmother Helen, and the reason she was sent from England.
Christie wrote this novel during World War II and wanted it to be published after her death. Originally titled Murder in Retrospect the title was changed after the publication of PD James Cover Her Face.
In 1987, the BBC made the book a two part television series, the 12th book to be adapted for the small screen and in 2001, was made into a radio play for the BBC.