Upon reaching the Venusian city of Aphrodite, Starr and Bigman meet Dr. Mel Morriss, head of the Council of Science on Venus, who explains that Venusian scientists are perfecting strains of yeast that can be processed into luxury foods for export; whereas for six months there has been a growing series of incidents of bizarre behavior among the human colonists, often followed by amnesia. Morriss believes they are being telepathically controlled by an unknown enemy. Evans was sent to Venus to investigate, but was found with stolen data concerning a secret strain of yeast, and is under arrest. When Starr confronts him, Evans admits to having stolen the data, but refuses to explain further. While Starr is questioning him, word reaches them that a man is threatening to open an outside airlock, which will allow the ocean to flood Aphrodite.