Most people have never heard of prions. Indeed, most are only barely aware of the diseases caused by them, except, perhaps, for mad cow disease. Yet prions are the stuff of a revolutionary science—a science that might lead to cures for some of humankind’s most devastating diseases. Fatal Flaws is a scientific detective story about this elusive protein, starting with the discovery of kuru, a disease unique to New Guinea in the 1950s that baffled scientists and carried with it whispers of cannibalism. Kuru began a scientific stampede to seek out the agent of this mysterious disease—the prion—a misfolded protein whose existence some of the world’s top scientists still find difficult to accept. Today, the subject of prions remains controversial, yet the proteins might promise new treatments for some of the most intractable brain diseases, ones that affect millions around the planet, including Parkinson’s, ALS and Alzheimer’s.