Catch a plane and begin a daring mission with these four radio super spies and sleuths. As Steve Mitchell, Brian Donlevy heads to London to keep enemy agents guessing in Dangerous Assignment (originally aired on NBC on March 3, 1951) and The Man Called X is off to Monte Carlo to find out why a fellow agent was killed (originally aired on NBC on May 4, 1951). Douglas Fairbanks, Jr. hunts for missing scientists and plans for the weapon they built in "The Gigantic Hoax" from The Silent Men (originally aired on NBC on January 20, 1952). And Mike Waring - aka The Falcon - is in Berlin on a job for Army intelligence in "The Case of the King of Clubs" (originally aired on NBC on July 20, 1952).