What happens
Jerry and Joan, along with Mrs. Gregory and Captain Bradford, remain in the undersea colony of Euclidea, where they are safe so long as they stay quietly within it. The group explores one of the large natural caverns, which holds pigs, chickens, grass and trees, and learns the reason these surroundings are kept natural. They meet Mac McLeod, the former yacht engineer, who is content tending his pigs and has no wish to leave. They are then brought before Carl Kiaps, the colony's builder, who claims to be a descendant of the architect of the Great Pyramid. Kiaps shows Captain Bradford a sheet of tempered copper leaf that will bear a man's weight.
Euclidea, a colony beneath the sea about 400 feet below the surface, housed in large natural caverns and steel-walled chambers.
Characters: Jerry, Joan, Mrs. Gregory, Captain Bradford, G-47, Mac McLeod, Carl Kiaps, Kriostra
Listen for: Carl Kiaps's claim to be the descendant of the Great Pyramid's builder and his demonstration of the tempered copper leaf.
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.