Behold, the story, in somewhat unpolished first version, as I once posted it years ago.
http://agathachristie.com/forum/have-your-say/miscellaneous/hearts-and-diamonds/reverse/ But as I said, it's somewhat unpolished, and thus rather crude (and someone was helpful enough to point out a few grammatical mistakes there, you can see).
Glossary of La ReinaismsAheheh: onomatopoeia for a chuckle, esp. a mischievous one
Hurm: onomatopoeia for thinking; a standard reply when all else fails
Spam: an all-purpose word