 The plot involves telepathy, speaking to animals, and, in the last few pages, an invasion by extraterrestrials.The nominal adversaries in the novel are known as "cow-dyes", a corruption of Caodai, a religion of Vietnamese origin.On the American side, telepaths, who are used in espionage and other covert activities, are falling victim to "the glotch", a fatal affliction which is believed to be a Caodai bio-weapon, transmitted telepathically.