There are a few things about "Danse Diabolique" that did not appeal to me. First, the plot idea is pretty silly....that a ballet called 'Danse Diabolique' is supposedly cursed and folks who dance it, die! This is silly...but also makes you wonder why anyone would take this risk. Second, a LOT of the episode consisted of ballet...which some will love and some will hate. I'm certainly not a fan and wanted to see more of Jessica Fletcher.
The ballet in San Francisco is going to perform this cursed dance. But it's pretty clear that the lady doing the dance will soon die, as she's awful and uses people (subtle, she isn't). And so, when she dies on opening night, this isn't much of a surprise. Jessica and the local detective work the case together.
If you love ballet, you'll likely appreciate this more than I did. But even if you do, the idea of a toxic dance is hard to believe...and make for a weak episode.