Agatha Christie must finish her autobiography and the final novel before the new year.

It is December 1975, after Christmas, and Agatha Christie must finish her autobiography and the final novel before the new year. Yet, Agatha is fixated on an event in her past when Nancy Neele stole her husband. With Mary Westmacott’s help, they contemplate what it would be like to kill Nancy. Even though Agatha considered murdering Nancy, did she really do it, or is her reality disappearing?