What happens
Superman has saved the planet Apollo and freed its people, but he has left a sealed letter revealing that Clark Kent is his secret identity with Dr. Millison, to be delivered to editor Perry White if Superman fails to return by a set day. Believing Superman lost in space, Dr. Millison brings the letter to the Daily Planet, where Perry White and Jimmy Olsen open it. Word then arrives that a planet resembling Apollo has been sighted, raising hope that Superman and Clark Kent are alive. Later, Superman returns to the observatory, learns the letter has reached the newspaper, and races to the Daily Planet. Clark Kent discovers the letter has vanished from the office.
Metropolis, at the Daily Planet newspaper office and a nearby observatory
Characters: Superman, Clark Kent, Perry White, Jimmy Olsen, Dr. Millison, Dr. Bloomfield, Lois Lane
Listen for: Clark Kent discovering that the sealed letter has disappeared from Perry White's office
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.