Mr. Keen, Tracer of Lost Persons was a captivating radio show that first premiered on the Blue Network. The program followed the story of a no-nonsense investigator, known only as Keen, who helps track down people who mysteriously vanish from their everyday lives. His trusty assistant Mike Clancy, a strong-willed Irishman, aids him in his disparate quests. The show evolved from its initial format as a thrice-weekly 15-minute serial, tackling baffling disappearances, to a humorous and entertaining program that saw Keen investigating murders in its half-hour week-long formula.

Broadcasted for 18 years, Mr. Keen, Tracer of Lost Persons aired from October 12, 1937, until September 26, 1955. It initially premiered on the Blue Network before transferring to CBS in 1942. Notable sponsors included Bisodol, Kolynos toothpaste, Chesterfield cigarettes, and American Chicle. Out of many episodes that aired during its run, nearly 60 recordings survive to this day for modern audiences to enjoy. The show's engaging format and memorable characters have made it popular with old-time radio fans even today.

Sources: archive.org, wikipedia.org, otrcat.com