Copy Boy (uncredited)
An ace reporter with a girlfriend nails a numbers racketeer for murders.
Robert Fletcher
Wonder Pictures has been striking out at the box office lately, causing the seedy PR man to involve main star Annabel in ever outrageous stunts for publicity.
Boy (uncredited)
Harvey, the arrogant and spoiled son of an indulgent absentee-father, falls overboard from a transatlantic steamship and is rescued by a fishing vessel on the Grand Banks. Harvey fails to persuade them to take him ashore, nor convince the crew of his wealth. The captain offers him a low-paid job, until they return to port, as part of the crew that turns him into a mature, considerate young man.
Junior
Dick Tracy's foe for this serial is the crime boss and Masked Mystery Villain The Spider/The Lame One and his Spider Ring. In the process of various crimes, including using his Flying wing and sound weapon to destroy the Bay Bridge in San Francisco and stealing an experimental "Speed Plane", the Spider captures Dick Tracy's brother, Gordon. The Spider's minion, Dr. Moloch, performs a brain operation on Gordon Tracy to turn him evil, making him secretly part of the Spider Ring and so turning brother against brother.
Kenneth Carpenter Jr. (as Lee Vanatta)
Kenneth discovers that his son by his first wife is ill in a remote Swiss village, and is forced to leave Wife Number Two alone during childbirth.
Billy Norton
Crash Corrigan, a recent graduate of Annapolis, and Diana, a go-getting reporter, join Professor Norton for a search for the source of a string of earthquakes, Atlantis. They ride Prof. Norton's rocket submarine searching the sea and little Billy Norton, the professor's son stows away, of course. When they find Atlantis they are caught in a war between peaceful Atlanteans, note their white capes, and war-monging Atlanteans, note their black capes. After many harrowing moments for Crash, Diana, Prof. Norton and Billy, they barely get away with their lives when they escape a tower of Atlantis raised to the surface for the sole purpose of dominating or destroying the Earth (Which one depends on the compliance of the upper world dwellers.)