Jonny accompanies his dad, Dr. Quest, to the mountains India, where several sheepherders have succumbed to a mysterious illness. The bad guys responsible for this epidemic -- caused by a deadly nerve gas -- subsequently target the Quests for extinction, leading to a pulse-pounding climax wherein Dr. Quest's new Ultra High Frequency Sonic Amplifier is deployed to save the day. As an added bonus, the story of how Hadji became part of the Quest team is told by way of flashbacks. Written by future movie-of-the-week stalwart Jo Anna Lee, "Calcutta Adventure" was originally scheduled to air on October 16, 1964, but was moved forward to October 30. ~ Hal Erickson, Rovi