What happens
Superman is racing against the clock to stop a threat to the Daily Planet building, which a masked villain known as the Yellow Mask has vowed to blow up before six o'clock. Reporters Clark Kent and Lois Lane visit scientist Dr. Sven Dahlgren, whose new atomic beam machine has been stolen. Dahlgren explains that the machine cannot work without atomic cylinders, which were kept in a safe. The reporters investigate a strange voice carried on a hidden radio relay, and a cut telephone wire suggests someone inside the house is involved. The episode is an installment of The Adventures of Superman, first broadcast on February 28, 1940, and the story is still unfolding when the segment ends.
Dr. Dahlgren's laboratory and house in the city, with the Daily Planet building nearby
Characters: Superman, Clark Kent, Lois Lane, Dr. Sven Dahlgren, Michael, Mr. White, The Yellow Mask
Listen for: The unseen voice on the radio relay and the sound of the steel doors opening
Written from the episode itself; it never gives away the ending. Every recording is remastered for the stream: cleaned of rumble, hiss and mains hum (and the old TV whine where we found it), then levelled in two passes to steady broadcast loudness, so one show is never quieter than the next.