Teaming up with his cousin Lucy, an epidemiologist who also has an independent mind, they discover that the authorities, a consortium of scientists, have been running secret trials on the population of the town. Through the addition of sodium ions to the water supply, the active population is gradually being made more chimpanzee-like, while the inactive, the old and the sick, are being euthanized. To Tom's particular disgust, the leaders of the trials are found to engage in sexual abuse of children, for which he takes his revenge by forcing them to drink high concentrations of sodium and so that they regress to apes.