It's time to sharpen those pencils and hit the books with four radio mysteries set in and around the classroom. First, a chemistry professor tries a blackmail experiment in "Hasty Conclusion" from The Whistler (originally aired on CBS on May 19, 1947) and Philip Marlowe's latest client is a Nebraska schoolteacher caught up in mystery and murder in "The Rustin Hickory" (originally aired on CBS on September 10, 1949). Then, Dana Andrews tries to thwart a Commie plot to infiltrate a college campus in "Little Red Schoolhouse" from I Was a Communist for the FBI and Joe Friday goes back to school to find an assailant targeting students in "The Big Knife" from Dragnet (originally aired on NBC on May 11, 1950).