Professor Kevin Fong was flying with the Helicopter Emergency Medical Service, making split-second, life-or-death decisions in the most extreme circumstances. Then he was seconded to the NHS's Covid-19 Strategy Unit, tasked with leading the fight against pandemic. In this gripping blend of memoir and reportage, he confronts a disturbing truth: the quest for 'zero harm' can prevent the saving of lives. Telling stories of astonishing skill and catastrophic error across medicine, aviation and space-flight, and reflecting on his own dramatic experiences as well as those of war medics, pilots and surgeons, Fong offers a visceral journey and a major new argument about the balance of safety and risk in the 21st century.