With 1690 episodes aired from October 12, 1937, to September 25, 1955, Mr. Keene, Tracer of Lost Persons was one of radio's longest running detective programs. It was based on the 1906 novel by robert W. Chambers Tracer of Lost Persons. The title role was first played by Bennett Kilpack; late in the series, the role was taken over by Philp Clarke, and then by Arthur Hughes. Keene (no first name) was a "kindly old investigator," who was assisted by Mike Clarke. portrayed by Jim Kelly. The show was heavy on dialogue and trite soap opera-ish plotting. It's popularity may have been due to its unintentionally bad production values.
In "The Skull and Crossbones Murder Case" a wealthy man is poisoned at his dinner table. Mr. Keene investigates.