This is the first book to penetrate the little-known world of the Epidemic Intelligence Service (EIS), an elite corps of young doctors, Ph.D.s and health professionals who have been on the scene of every major epidemic in the past half-century. McKenna shadows the first group to join the EIS after Sept. 11, 2001. She follows them across the United States and to Africa and Asia, revealing their exhaustion, frustration, occasional fear – and exhilaration when they solve a mystery in time to save lives.