The board of directors of an aircraft company has been receiving threats via skywriting from a mysterious figure known only as "The Eagle". The owner of a traveling carnival, with a grudge against the company, is suspected of being the criminal. When strange circumstances begin to befall the aircraft company and the carnival, the carnival owner's disappearance springs the carnival's stunt pilot and his girlfriend, the carnival owner's daughter, into action to find him and prove his innocence.

Episodes: (1) The Carnival Mystery (2) Pinholes (3) The Eagle Strikes (4) The Man of a Million Voices (5) The Telephone Cipher (6) The Code of the Carnival (7) Eagle or Vulture? (8) On the Spot (9) When Thieves Fall Out (10) The Man Who Knew (11) The Eagle's Wings (12) The Shadow Unmasked