 The Mutual Broadcasting System ( commonly referred to simply as Mutual ; sometimes referred to as MBS , the Mutual Broadcasting Company , or the Mutual Radio Network ; corporate name Mutual Broadcasting System , Inc . ) was an American radio network in operation from 1934 to 1999 . In the golden age of U.S. radio drama , Mutual was best known as the home of such popular series such as The Whistler , The Whistler , The Whistler , The Whistler , The Whistler , The Whistler , The Whistler , The Whistler , The Whistler , The Whistler , The Whistler , The