Previously on Mystery*File, Ray O’Leary did a fine review of John Curran’s Agatha Christie’s Secret Notebooks, and you’re urged to read it.

   In his book, Curran includes two previously unpublished short stories featuring Hercule Poirot and speculates about when and why these tales were never published. In his review, O’Leary suggests equally valid speculations.

       (1) “The Capture of Cerberus”

   Readers might like to compare this version dating from 1939 with the one that finally saw print in 1947. As Curran notes, this story has a “complicated history.”

   In Geneva, Poirot happens to encounter an old nemesis-turned-friend, Countess Vera Rossakoff. Predictably, there is a male admirer trailing in her wake, Herr Doktor Keiserbach; but it would seem that Keiserbach has been using the countess as a means of meeting the little Belgian.

   Keiserbach later tells Poirot his true identity, and entreats the detective to help clear his murdered son’s name for having assassinated a popular but controversial European politician, a double for Adolf Hitler.

   In true Christie fashion, doubles figure prominently in the plot, with Poirot contriving an intricate plan to find a dead man and convince him to come back to life, while at the same time vindicating Keiserbach’s son.

   Last time we checked, you could read a portion of “Cerberus” online here. Presumably Christie’s revised version, which differs radically from the original, has somehow recently been adapted for the television series, Agatha Christie’s Poirot.

       (2) “The Incident of the Dog’s Ball”

   Based on surer evidence than is available for “Cerberus,” Curran surmises that this story “was written in 1933 and never offered for publication but, instead, transformed, in 1935/36, into the novel Dumb Witness.” With the transformation, Christie changed both the murderer and the solution.

   Captain Hastings narrates the story. When Poirot receives an almost incoherent letter from an elderly woman, his little grey cells are set aquiver. It being hot and sultry in London, a dubious Hastings nevertheless welcomes the chance to quit the city for the more tolerable hinterlands when Poirot suggests they find out more about this woman.

   Not long after arriving in Little Hemel, Poirot is crestfallen to learn of the old lady’s death, and he finds it inexplicable that she should will her estate, not to her closest relatives, but to a paid companion who is, let’s be honest, a little flaky.

   The little grey cells inform the Belgian sleuth that all is not as it appears to be in this affair, and a series of seemingly unrelated clues — including a toy ball — lead him to conclude the elderly woman was murdered.

   Bob, the titular canine, comes by implication to be a murder suspect himself; and the fact that the village doctor can’t smell most odors will help the real murderer escape suspicion — but only for a while, because the indefatigable Hercule Poirot is on the case.

   Christie’s final version of this story was filmed for TV as “Dumb Witness” in 1996.