Biologists Dr. Mary Robinson (Janice Logan) and Dr. Rupert Bulfinch (Charles Halton) are summoned by Dr. Alexander Thorkel (Albert Dekker) to his remote laboratory in the Peruvian jungle. They are accompanied by mineralogist Dr. Bill Stockton (Thomas Coley), a friend of Mary's and a last minute substitute for another scientist, and Steve Baker (Victor Kilian), who wants to make sure his hired mules are well cared for (and suspects Thorkel may have discovered a rich mine). When they arrive, Thorkel asks the scientists to describe a specimen in his microscope, since his eyesight is too poor for him to do so himself. Bill identifies iron crystal contamination, much to Thorkel's satisfaction. Then, to their astonishment, Thorkel thanks them for their services and wants them to leave.