Superman returns in this week's bonus episode! A brilliant scientist and explorer has disappeared, and Clark Kent joins the man's daughter as she investigates. The pair travel to the scientist's remote mansion, where they discover a priceless relic and come under attack from a secret society who will kill to get it back in these episodes that aired between April 1 and 12, 1940. Plus, we'll hear a bonus half-hour adventure of Superman - "The Case of Double Trouble" (originally aired on ABC on March 9, 1949).