Some years ago, while living in London, Faye Hueston became mysteriously ill. Unable to find a cause for her peculiar symptoms, doctors dismissed them as psychosomatic. Eventually, tests by a clinical ecology doctor proved the cause to be pesticide poisoning. Invisible Enemy refers to the chemicals that are polluting our bodies as well as the environment. Based on the diaries Faye Hueston kept at the time, it chronicles her experience of environmental illness and her long, often frustrating, search for a cure.