The Disappearance of Mr Davenheim

A city banker called Mr Davenheim vanishes without explanation, and the case is strange enough to reach Japp, who brings it to Poirot in a challenging mood. The disappearance is the talk of the City, and the City does not forget a vanished banker. The inspector lays a wager that Poirot cannot solve it without leaving his flat. The bet is Japp's idea of a joke, and Poirot's idea of an insult to his methods. Poirot, who values his reputation and his armchair in roughly equal measure, accepts.

The rest of the episode is deduction at one remove. Poirot questions everyone who comes to call, sends Hastings out to gather what the flat cannot supply, and turns the missing banker's life over in his mind until the answer surfaces. Each caller adds a fact, and each fact removes an innocent. The circle is small and close: Charlotte Davenheim, Mathew Davenheim, Gerald Lowen, a maid, Merritt, a sergeant with a notebook. And yet everything about the case ends up on the table in front of him without his ever leaving the chair.

David Renwick and Agatha Christie wrote it, Andrew Grieve directed. Mel Martin plays Charlotte Davenheim, Kenneth Colley is Mathew Davenheim, Tony Mathews plays Gerald Lowen, Fiona McArthur is the maid, Richard Beale plays Merritt and Bob Mason is the sergeant. David Suchet is Poirot, Hugh Fraser is Hastings, Philip Jackson is Japp and Pauline Moran is Miss Lemon.

The wager gives the episode its shape and its charm. There is something deeply satisfying about a mystery solved without a single visit to the scene, a reminder that the little grey cells do not need to travel. The flat becomes a courtroom one moment and a confession booth the next. Japp should have known better than to bet against them.