What happens
Lois Lane and Horatio Horn, investigating a red-eyed sea monster that has terrified the Canadian village of St. Selmo, are nearly killed when their chartered boat is rammed and set on fire. Superman rescues them, then goes off on his own after the creature. Clark Kent, once back in Metropolis, takes a sample of seawater from the fishing banks to the city chemist, Ben Jacob, for analysis. Ben has found something in the water that may explain the mystery, and Clark is eager to hear the result. The broadcast is the Adventures of Superman, part six of the Phantom of the Sea story, first aired on May 5, 1947.
St. Selmo, a small Canadian coastal village, and later Metropolis
Characters: Superman, Clark Kent, Lois Lane, Horatio Horn, Mr. Barnaby, Ben Jacob
Listen for: Clark Kent's sample of seawater and what the chemist Ben Jacob finds in it
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.