The Adventures of Sam Spade was a radio drama series that blended humor with crime drama, following San Francisco private detective Sam Spade as he solved various cases with witty dialogue and clever plots. In 'The Biddle Riddle Caper,' Sam Spade is hired by a radio producer to help solve a three-year-old murder case, discovering a reel of recording tape cleverly disguised as a typewriter ribbon and using this recorded evidence to expose the killer.