Quickstep to Murder, by Ella Barrick

I like mysteries that contextualize the formula within some strange (to me) subculture, or other time or place.  I realized reading Barrick's book how important it is that the writer know enough about that context that the readers feel like they are learning something.  Barrick doesn't know that much about ballroom dancing.  She and her husband took lessons for a while, and attend the competitions, but she tries to paint characters who are single-minded about dancing.  She often prefaces some pretty uninsightful observations with "Most people don't realize"... that ballroom dancers pay a lot for their costumes... work out incessantly... wear a lot of make up...  I don't feel like I learned anything new about the ballroom dancing world.  On the other happier hand, Barrick writes wittily and well, and her plotting was perfectly fine.