The Adventures of Sam Spade was a suspense/detective radio show starring Howard Duff in the colorful title role along with Lurene Tuttle as his secretary Effie.  It was based on the private detective character created by Dashiell Hammett, well-known from the book and movie The Maltese Falcon.  The show ran from 1946 to 1951.  Duff was replaced by Steve Dunne in later episodes. The Mad Scientist Caper: A slightly insane inventor hires spade to recover his secret formula. Originally aired July 25,1948Support the show (https://www.buymeacoffee.com/steviek)