When our radio sleuths check the mailbox this week, they're getting a special delivery of danger! Missing messages, anonymous letters, and mysterious correspondence drive the cases in this week's showcase of old time radio detective dramas. First, Tom Conway is Holmes and Nigel Bruce is Watson in "The Adventure of the Tolling Bell" from The New Adventures of Sherlock Holmes (originally aired on ABC on April 7, 1947). Next, Alan Ladd answers a letter to Box 13 in the syndicated show "Double Trouble." Then, radio's singing sleuth tries to find out who killed the messenger with Dick Powell in Richard Diamond, Private Detective (originally aired on NBC on April 19, 1950). And finally, Bob Bailey is George Valentine, who receives a letter from a woman asking him to catch her killer...but she isn't dead yet in "The White Elephant" from Let George Do It (originally aired on Mutual on September 11, 1950).