Murder by Death

The other unpublished work that was included in Agatha Christie's Secret Notebooks, The Mystery of the Dog's Ball was actually the basis for Christie's full-length novel Dumb Witness (1937).  The character's names are different, but apparently several scenes are identical.

I won't say this short story is without it's problems - it is, including the large leaps of imagination the reader must make to really make the plot work, but I found this one to be a more fully thought-out story than The Capture of Cerberus.  The ending might leave some dissatisfied but I think it added a dimension to the story, keeping it from becoming a cliched mystery where everything is wrapped up in a HEA resolution.