Edna May Oliver is one of those ubiquitous character actors seen in films of the 30's and early 40's. You're probably familiar with her from the 1933 classic Little Women with Katherine Hepburn (she played Aunt March) and Pride and Prejudice (1940) with Greer Garson (she played Lady Catherine). Before she moved over to the greener pastures of MGM, she was a contract player at RKO, where she was cast as the lead in a series of films based on the Stuart Palmer novels about a crime solving schoolmarm. There were three of them, beginning with the Penguin Pool Murder (1932), followed up by Murder on the Blackboard (1934) and Murder on a Honeymoon (1935). Assisted ably by her detective/boyfriend played by James Gleason, Hildegarde perseveres to solve the crime and save the day.
The films are pretty fluffy, but have a fun, 1930's quality to them that makes them enjoyable to watch. They were recently on TCM in a celebration of Ms. Oliver's birthday. But while the books are still available, the films are not released on DVD. When Ms. Oliver decamped for MGM they tried to recast Ms. Withers with Helen Broderick and Zasu Pitts, but no one could embody Hildegarde like Edna May - at least until 1972 when the inimitable Eve Arden played the part in a made-for-TV movie that has persisted in eluding me. Watch for a post on that one sometime in the future! The poster above can be purchased at MoviePosterShop.com.
Obscurity factor: 7 (not available on DVD, occasionally aired on television, not available on YouTube)