On a cold day in December 1667 the renegade physician Jean Denis transfused ten ounces of calf's blood into Antoine Mauroy, a madman. Several days and several transfusions later, Mauroy was dead and Denis was framed for murder. A riveting and wide-reaching history, Blood Workshows how blood transfusion became swept up in personal vendettas, international intrigues, and the war between science and superstition. In a foreshadowing of today's stem cell and cloning debates, proponents saw transfusion as a long-awaited cure to deadly illnesses, while others worried that science was toying with forces of nature, perhaps even paving the way for monstrous hybrid creatures. Taking us from the highest ranks of society to the lowest, Holly Tucker introduces us to an unforgettable cast of characters, all ruthless contenders in the battle over transfusion. Finally, in a feat of historical research, she reveals the true identities of Mauroy's murderers—and their motivations to kill.