Though it wasn't RKO Radio's final "Hildegarde Withers" mystery, Murder on a Honeymoon represented the final appearance of Edna May Oliver as Stuart Palmer's spinsterish schoolmarm sleuth. This entry was wittily adapted by Seton I. Miller and Robert Benchley from Palmer's Puzzle of the Pepper Tree. Vacationing in Catalina (where much of the film was shot), Hildegarde Withers gets mixed up in three murders. Her old friend, New York detective Oscar Piper (James Gleason), flies out to help, but of course it's Hildegarde who cracks the case. The top-heavy list of suspects includes one disreputable character who overpowers the formidable Hildegarde and locks her in a closet -- proving beyond all doubt that he's not the guilty party. After Murder on a Honeymoon, Oliver relinquished the role of Hildegarde to Helen Broderick and (of all people) ZaSu Pitts.