E G MARSHALL...CBS MYSTERY THEATER

 The format was similar to that of classic old time radio shows like The Mysterious Traveler and The Whistler, in that the episodes were introduced by host E. G. Marshall who provided pithy wisdom and commentary throughout. Unlike the hosts of those earlier programs, Marshall is fully mortal, merely someone whose heightened insight and erudition plunge the listener into the world of the macabre.

As with Himan Brown's prior Inner Sanctum Mysteries, each episode of CBS Radio Mystery Theater opened and closed with the ominous sound of a creaking door. This sound effect is accompanied by Marshall's greeting, "Come in!… Welcome. I'm E. G. Marshall." At each show's conclusion, the door swings shut, and Marshall signs off with: "Until next time, pleasant… dreams?" This is followed by an extended variation of the show's theme music.

CBSRMT was broadcast each weeknight, at first with a new program each night. Later in the run, three or four episodes were new originals each week, and the remainder repeats. There were 1,399 original episodes. The total number of broadcasts, including repeats, was 2,969. Each episode was allotted a full hour of airtime, but after commercials and newscasts, each episode typically ran for around 45 minutes.E. G. Marshall  was an American actor, best known for his television roles as the lawyer Lawrence Preston on The Defenders in the 1960s and as neurosurgeon David Craig on The Bold Ones: The New Doctors in the 1970s. Among his film roles he is perhaps best known as the unflappable, conscientious "Juror #4" in Sidney Lumet's courtroom drama 12 Angry Men (1957). He played the President of the United States in Superman II (1980). Marshall was also known as the host of the radio drama series, CBS Radio Mystery Theater (1974–82).