The Zero Hour (aka Hollywood Radio Theater) was a 1973–74 American radio drama anthology series hosted by Rod Serling. With tales of mystery, adventure and suspense, the program was broadcast for two seasons. Some of the scripts were written by Serling. In 1974, still airing five days a week, the program changed to a full story in a single 30-minute installment with the same actor starring throughout the week in all five programs. That format was employed from late April 1974 to the end of the series in July 1974. Highbridge Audio has released some of the five-part stories on audiocassettes.