The title of this Avengers episode refers to a new liquid rocket fuel. Assigned to rendezvous with the man delivering the fuel to the Government, Steed and Cathy discover that the man has been murdered. They spend the rest of the episode trying to wrest the fuel from the hands of enemy agents, cornering their quarry in a bakery where Cathy deploys a most unusual concealed weapon. Written by Jon Manchip White, "Propellent 23" was originally telecast in England on October 6, 1962; its first American appearance didn't take place until January 28, 1991. ~ Hal Erickson, Rovi