What happens
Clark Kent, a reporter for the Daily Planet, is called into editor Perry White's office and meets Professor A.B. Thorpe, an inventor of a deep-sea diving device called the bathysphere. The professor is sailing from Key West to San Matamonica, but he learns that his ship has left port early without him. Kent offers to fly him after the vessel in a seaplane. When they catch up, the ship's captain, Maddox, fires on the plane, and Thorpe falls into the water. Kent rescues him and they board the ship, where Maddox produces a telegram ordering the ship to sail without the professor. Kent and Thorpe then hear tapping from the ship's hold that seems to be an SOS signal.
Metropolis, the Daily Planet offices, Key West, and the ship Juanita in the Caribbean Sea
Characters: Clark Kent, Perry White, Professor A.B. Thorpe, Captain Maddox, Superman
Listen for: The tapping from beneath the cabin floor and the telegram Maddox produces
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.