Jim and his fellow adventurers are on the last lap of a perilous mission deep into South America to aid Don Jose O'Reilly, the father of their young companion, Ramon. Mysterious foes have repeatedly sought to stop their rescue attempts, and now Jim and his friends have had to continue on foot after their automobile was wrecked during a gunfight. Lil was seeking to quench her thirst by chewing on a leaf in the jungle, but unfortunately she is now stricken with acute poisoning...