Sacks is once again travelling in search of human diversity,this time to the islands of the Pacific Ocean. Islands have always facinated him as places which are mysterious, intensely attractive, yet frightening. Colour is another of his lifelong interests and now he is looking at people who have been colour-blind from birth and what perception they have of the visual world. To find the answer, he went to Pingelap, a tiny atoll among the Pacific Islands, where congenital achromatopsia has affected a suprisingly high proportion of the population, resulting in a colour-blind community.
He then went to Guam to study the strange neurological disease that has been endemic there for more than a century. Called lytico by the native Chamorros, it again afflicts a startlingly high proportion of the inhabitants with profound, progressive and fatal muscular weakness. Could the cause be the cycads which grow on Guam and which form the islanders' staple diet?
Once again Oliver Sacks combines his neurologist's knowledge and curiosity with his own obsessions to give a spellbinding account of a quest into science, history, geography and anthropology.