The Man Who Knew

The Man Who Knew is an early  Agatha Christie short story believed to have been written shortly  after the First World War, probably before The Mysterious Affair at Styles was penned. The short story was never published in Christie's life time but she reworked it and expanded it into The Red Signal which was published in 1924.

The Man Who Knew was eventually published in John Curran's Agatha Christie's Secret Notebooks: Fifty Years of Mysteries in the Making in 2009. It was also included in the collection Bodies from the Library 2: Forgotten Stories of Mystery and Suspense by the Queens of Crime and other Masters of Golden Age Detection published by Collins Crime Club in 2019.