Production Code ..... 8620 Air Date ..... April 4, 1967 Writer ..... Jameson Brewer Director ..... Richard C. Bennett Murray Matheson ..... Dr. Merek Julie Adams ..... Unknown       April poses as an airline stewardess; Mark is disguised as a big game hunter. Both are on board a plane carrying a number of scientists to a Council of World Scientists meeting. One doctor aboard has developed a substance that, carried by harmless birds, can cause slow death to humans. Also on the same flight is the doctor who has developed the antidote. Waverly fears a confrontation between the two hence April and Mark on the scene.