Epidemic! It began in the peaceful pastures of Wisconsin. Death had occurred from contaminated milk and dairy products, and the farmers stood by helplessly as their herds were condemned and slaughtered on nothing more than "suspicion." U.S. Public Health Service official Dr. Creighton Thornesby had "personally" supervised the shooting of the cattle. He wanted to prevent future outbreaks—or did he? Only the Penetrator knew who Thornesby really was—and he had to stop the deranged doctor from carrying out his insane plan to control the world through germ warfare...before everybody on earth was exposed to the virulent Bubonic Plague!