 William Morrow and Harper Audio present, An Elegant Defense, The Extraordinary New Science of the Immune System, A Tale in Four Lives, by Matt Richtel, read by Fred Sanders. Authors Note To distinguish between medical doctors and PhDs, I refer to medical doctors with the honorific doctor, whereas I refer to PhDs solely by last name. This is a painful tradeoff, given that PhDs not only have attained hard-earned doctorates, but have made the most important discoveries in this field. I made the decision, following an informal New York Times style, in order to help guide the listener through a story with multiple characters, some with research expertise, tending to be PhDs, and others with clinical expertise, tending to be physicians. I beg the indulgence of the scientists who are chief among this Odyssey's Argonauts. Finally, I've used first names for Jason Greenstein, his family and friends, and for others whose intimacies I've shared, including Bob Hoff, Linda Seeger, and Meredith Branscombe. The personal nature of their medical tales calls for more casual language. Part 1 Lives in the Balance CHAPTER I Jason. A gray sky overhead. Jason Greenstein sat silently in the passenger seat of a Ford Windstar. It was Friday, March 13, 2015. Jason was heading to a miracle and traveling in the style to which he had become accustomed. Filth. His silver minivan, fast approaching Denver from its suburbs, looked like scrap metal on wheels. The heater coughed and spat and seemed to work only when it was hot outside. The backdoor didn't open. Various warning lights dotted the dashboard, alerting Jason to system failures he ignored. His maps and atlases overflowed compartments and littered the floor. Sample complete. Ready to continue?