The Adventure of Johnnie Waverly

A country squire receives a letter threatening to take his son, and Poirot, hired to stop the kidnapping, does everything in his power to make sure it cannot happen. It happens anyway. Johnnie Waverly vanishes from under the household's nose, and for a while it looks like a rare failure for the great detective. The letter is specific enough to frighten a father and vague enough to baffle the police.

But it is not a failure, and the episode enjoys letting the audience squirm before the reveal. The ransom note arrives, and here the case splits along familiar lines: Chief Inspector Japp refuses to treat it as a threat to public order, while Poirot reads it the way he reads everything, as a message from a particular mind with particular habits. He treats the note as a piece of handwriting rather than a demand, and handwriting does not lie the way people do. The disagreement drives the investigation, and Hastings trots along offering the kind of theory that exists to be dismantled.

Clive Exton and Agatha Christie wrote the script and Renny Rye directed. David Suchet is Poirot, Hugh Fraser is Hastings, Philip Jackson is Japp and Pauline Moran is Miss Lemon. The household itself is played by Geoffrey Bateman's Marcus Waverly, Julia Chambers's Ada Waverly, Dominic Rougier's Johnnie, Patrick Jordan's Tredwell, Carol Frazer's Jessie Withers and Sandra Freeman's Miss Collins.

The kidnapping could have been played for melodrama. The show keeps it quiet and lets the puzzle breathe, and the moment the failed plan turns out to have been the plan is as neat as anything in the first series. The high stakes give the puzzle its teeth, but the episode is really about how a family's private arrangements look from the outside. The country house and the ransom note: the story is built from the quietest possible parts.