[ As mentioned earlier, these posts will contain spoilers. I do recommend you read the stories involved, because they're good and they're short ]
The original story of Hercules and the Nemean Lion was simple: go kill this ginormous lion that's been gnawing on the peasantry. After an arrow or two, Hercules discovers that the lion, like Achilles, has an impenetrable hide. Unlike the entire freaking Trojan army, he realized that the solution was to simply (depending on the version) either strangle it or beat it to death -- no need to break the skin! He then used the beast's own claws to skin it, and thereafter wore its hide (somewhat ineffectively) as armor. That's a big cloak to fill for the little Belgian detective!
Hercule Poirot's version of the tale is rather more mundane. His attention is caught one morning by a letter set aside by his secretary: a society lady has lost her Pekinese dog. Not exactly the stuff of legends. And yet he is intrigued, for while he receives no end of letters from society ladies who have lost their yapping little dogs, this is the first he has received from one of their husbands!
Things get more interesting: the dog has already been recovered! The husband (Sir Joseph Hoggin) objects, rather, to his wife having paid the £200 (without consulting him), discovered that one of his friends' wives had paid £300 over a similar kidnapping and wishes the thief to be caught. His wife objects to bringing in the police, so Poirot is consulted.
Poirot interviews Lady Hoggin and her companion, an older and somewhat batty woman named Carnaby who is much put-upon, not least because she was the one who was walking the dog at the time of its capture. There's some observation of the pair, and the cut leash is produced. Poirot then interviews the companion's references, visits both the scene of the kidnapping and the hotel where the money was to be sent, goes to visit the other victim (another society lady with a Pekinese and a timid put-upon companion), and goes home. From home, he instructs his valet to make certain investigations (we are not at this point privy to the instructions) and an address is produced. Poirot arrives at the address and finds the first companion, Amy Carnaby, along with her invalid sister... and a third Pekinese dog.
The plot, then, had been simple: Carnaby had taken advantage of being called upon to walk her employer's dog. She brought the dog home, then walked her own dog, Augustus. She'd go to the park, be seen by lots of people, then cut the leash. Augustus, being well-trained, would simply trot home, and she would make a big scene, then tell her employer that she'd been distracted by a baby in a perambulator. She had in fact done this many times, enlisting friends of hers whose employers owned Pekinese dogs, and sharing the ransoms in a pool. Augustus, the Nemean Lion of the story, had a hide that made him not invulnerable, but invisible: one yappy dog looks just like another, after all.
I estimate the length of the story (25 mass-market paperback pages at the standard 250 words per page estimation) to be between 6,000 and 7,000 words: just about the length I'm hoping to learn about. The simplicity of the plot seems to be a major help. And Christie has developed a number of ways to get a lot of information across quickly. For example, by naming the second Pekinese dog "Nanki Poo" she really doesn't need to describe the dog's owner very thoroughly: the reader already has a very clear image of the sort of people who give Pekinese dogs that sort of name. In fact, she gets a lot of mileage out of stereotypes.
One thing that fascinated me is that she didn't make use of all the clues she dropped. Poirot didn't explain himself that much when he confronted Carnaby. Two clues in particular were not mentioned: there was a nod to Conan Doyle in that the stolen dog did not yap at its kidnapper (though instead of knowing the kidnapper -- yappy dogs yap at everyone anyway -- there was no kidnapper), and the fact that the case involving Carnaby was for less money than the others (she was not splitting the money with an extra partner). I think that last one was important, as there is otherwise a bit of a plot hole: if there really were dozens of these kidnappings, who's to say Carnaby was the mastermind and not just one of the serial accomplices? But then, paying the money into a pool seems to defeat this, perhaps this is a remnant of an early draft? Either way, there's a kind of confidence at work in letting clues slide that I don't think I developed in my own stories. I'll have to give this some serious thought.
The final lesson from this story is the significant role played by inter-personal relationships. The story revolves around how wealthy society ladies relate to the world: their relationships to their paid companions, to their husbands, and to their dogs. All combine to expose a neat little blind spot through which money may escape. The relationships and the results need very little in the way of explanation.
All told, a neat little story. By having a fairly simple mystery behind the scenes and leaning pretty heavily on the personal relationships, Christie had a lot of space in which to work. She was also very clever in identifying which bits of the story did not need to be shared: no need to go into the effort to track down Carnaby's invalid sister, for example, nor more than one other kidnapped Pekinese to establish the pattern. So, by keeping these details to a minimum, using easily-grasped personal relationships, and not even going into all the clues, there was plenty of room for setting and texture (not to mention a subplot I haven't gone into here!).