It is well dressed but dreadful and unbelievable with a ridiculous story.
I am astounded at all the positive comments in the other thread.
i don't think any of the stories( and also the episodes) in this series are to be taken too seriously.
they are great entertainment and intended as a sort of parodies of detective fiction. not to mention the added attraction of utterly charming francesca annis in episodes.
i find most of stories in cristie's other mystery series (like poirot and marple) which were intended seriously, much more silly and ridiculous because of unbelievably absurd complex plots, with unrealistic elements such as overuse of impersonations, and not quite logically sound 'solutions'.
here, at least, she is laughing at her work.