Through a selection of case studies written like medical mysteries, neurologist Peskin illustrates the terrifying effects of the tiniest changes: from the gene-directed protein synthesis that results in Huntington’s chorea, to a woman whose own immune system flooded her brain with hallucinogens, to a patient whose grip on reality was threatened by what turned out to be a simple vitamin deficiency, this book left me amazed both at the delicate balance our bodies must tread to maintain our brains.