Death at the Bar by Ngaio Marsh
My rating: 4 of 5 stars
I didn't figure this one out at all. Once Inspector Alleyn explained what happened it was clear as glass, but before that I had suspicions of nearly everyone. Very well done!
This title counts toward the Vintage Mysteries Challenge in the category of Scene of the Crime: a book with the location of the crime in the title (The Body in the Library, Murder at the Vicarage, etc.)