In Dark Winter, world-leading epidemiologist Professor Raina MacIntyre navigates the past, present, and future of pandemics and biosecurity. MacIntyre examines the history of biological warfare (and why it is called the 'poor man's nuke'), Soviet and US bioweapons programs, developments in genetic engineering, synthetic biology, and catastrophic laboratory accidents. She also explores the COVID-19 pandemic and the heated debate around its origins, and shares the analysis she has conducted in trying to determine whether it's a natural or unnatural pandemic. Looking ahead, MacIntyre outlines the future of genetic engineering, synthetic biology, and bioterrorism, and the national and global security needed to manage quantum changes in technology, along with how we might avoid future pandemics.