Deep within the clandestine laboratories of Los Alamos, a fourteen-pound sphere of solid plutonium sat on a table, waiting to be pushed to the brink of a nuclear chain reaction. The scientists who built the world's first atomic weapons called it "tickling the dragon's tail." The Demon Core is the terrifying true story of how unparalleled intellectual brilliance collided with shocking physical recklessness. In 1945 and 1946, two separate physicists, Harry Daghlian and Louis Slotin, accidentally triggered lethal bursts of radiation from the exact same plutonium core. Rather than using precise mechanical safety protocols, they manipulated the volatile metal with ordinary flathead screwdrivers and bare hands. A single slip of the wrist was all it took to seal their agonizing fates. This book dissects the horrifying physics of criticality accidents and the psychological arrogance that plagued the early atomic frontier. It reveals how the men who understood the terrifying power of radiation better than anyone else on Earth routinely ignored their own safety warnings. Explore the gripping, tragic history of the most dangerous object ever created, and witness how human overconfidence turned a triumph of science into an instrument of personal destruction.