This study tells the behind-the-scenes story of the invention of the PCR, the polymerase chain reaction. Blending narrative description and interviews with all the major players, Paul Rabinow explores what it means to be a scientist today, the effects of carrying out science in the high-risk, high-reward environment of biotech, and what a scientific discovery or invention is these days, when it is possible to patent life itself. PCR has transformed the world of molecular biology, allowing scientists to make millions of copies of any part of a gene. This guarantee of an essentially unlimited supply of genetic material is useful to modern research. The work explores the culture of biotechnology as it emerged at Cetus Corporation during the 1980s. Entrepreneurial research scientists were interacting with investors, gambling billions of dollars on hot discoveries. Rabinow interviews the cast of characters who made PCR, including Kary Mullis, the maverick who received the Nobel Prize for discovering PCR but did not do it alone; Tom White, the inspired and careful researcher who helped transform PCR from an idea into a scientific tool; and Robert Fildes, who struggled to measure innovation against profit in managing Cetus in the heady early days of biotech.