I read cozy and historical mysteries, a bit of Paranormal/UF, and to mix it up, I read science and gardening books on occasion.
The other unpublished work that was included in Agatha Christie's Secret Notebooks, The Mystery of the Dog's Ball was actually the basis for Christie's full-length novel Dumb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.