Yuen Kwok-Yung rose to international prominence as an academic, physician, and microbiologist. As an advisor to governments, he and colleagues made discoveries that helped the world cope in often controversial ways with unprecedented threats to public health, including the COVID-19 pandemic. In this compelling memoir, Dr. Yuen weaves personal stories with those from his extraordinary medical careers to take readers on an inspiring journey about perseverance, courage, faith, and the ongoing peril of infectious diseases.