Each episode opened with the haunting theme whistled in 13 notes by Dorothy Roberts. For most of the series' run Bill Forman played "The Whistler," who served as each episode's host and narrator. "I am the Whistler," he intoned ominously, "and I know many things for I walk by night. I know many strange tales, many secrets hidden in the hearts of men and women who have stepped into the shadows. Yes, I know the nameless terrors of which they dare not speak."
The stories then followed an effective formula in which a person's criminal acts were typically undone by their own stupidity; ironic twist endings were common. The Whistler narrated, often commenting directly upon the action in the manner of a Greek chorus, taunting the criminal from an omniscient perspective.
Unlike Suspense, The Whistler never featured any major Hollywood stars. But the quality of its writing and performance made it a radio mainstay that is greatly admired to this day.