Agatha Christie’s Secret Notebooks: Fifty Years of Mysteries in the Making - Includes Two Unpublished Poirot Stories. John Curran

Body in the Library—Miss Marple [The Body in the Library]

      U. Stored blood idea, wrong blood

      A few pages later, the germ of the plot emerges although, as can be seen from the question marks, the idea was hazy. As we saw in Chapter 3, Christie considered a multitude of possibilities in working out its plot. But apart from a name change this short musing is the basis of the novel: