This episoded aired on CBS Radio January 6, 1944. Mr. Keen: Tracer of Lost Persons. Mr. Keen’s in the deep South to find a missing southern gentleman on a plantation with black walnut trees. Bennett Kilpack, Frank Hummert, Anne Hummert, Larry Elliott (announcer). Mr. Keen, Tracer of Lost Persons was one of radio's longest running shows, airing October 12, 1937 to April 19, 1955, continuing well into the television era. It was produced by Frank and Anne Hummert, who based it upon Robert W. Chambers' 1906 novel The Tracer of Lost Persons. More from WIKIPEDIA: https://en.wikipedia.org/wiki/Mr._Keen,_Tracer_of_Lost_Persons