For reasons unknown, a certain species of birds -- the martlets -- is disappearing from the face of the earth. Investigating this curious turn of events, as well as a sudden rash of crop failures, Steed and Emma cross the path of a most politically incorrect gentleman, who is in a cahoots with a band of biological terrorists. Faced with an ultimatum and a deadline -- pay forty million pounds, or suffer horrible consequences -- the British government must rely upon The Avengers to make the world safe for martlets once more. Written by Roger Marshall, "Silent Dust" was originally shown in England on January 1, 1966; though it was never seen on American network television, the episode was later included in the series' syndicated package. ~ Hal Erickson, Rovi