The book is an alternate history novel that explores a world in which the Black Death plague of the 14th century was far more lethal to Europeans, nearly wiping them out. As a result, world history is dramatically reshaped: Islamic and Buddhist societies emerge as the dominant global powers, leading to vastly different technological, cultural, and social developments. The narrative spans several centuries, following a group of characters who are reincarnated into various lives and roles, allowing the reader to experience the evolution of this alternate world through their interconnected stories. The novel delves into themes of history, religion, technology, and human nature, all while imagining a world both familiar and strange, shaped by different forces and ideas than those that have shaped our own history.

The book challenges common misconceptions about the state of the world, using a wealth of statistical data to argue that, contrary to popular belief, global living conditions are improving significantly. It introduces ten instincts that distort our perspective—from the fear instinct (which leads us to perceive the world as more frightening than it is) to the destiny instinct (which causes us to assume that the fates of populations are predetermined). The author, a renowned public health expert, encourages readers to adopt a "factful" mindset, which relies on data and evidence to create a more accurate understanding of the world, ultimately fostering a more positive and productive approach to global challenges.