Carl Zimmer investigates one of the biggest questions of all: What is life? The answer seems obvious until you try to seriously answer it. Is the apple sitting on your kitchen counter alive, or is only the apple tree it came from deserving of the word? If we can't answer that questions here on Earth, how will we know when and if we discover alien life on other worlds? The question hangs over some of society's most charged conflicts - whether a fertilized egg is a living person, for example, and when we ought to declare a person legally dead. Here is an utterly fascinating investigation that no one but one of our most celebrated, artful science writers could craft. Zimmer journeys through the strange experiments that have attempted to re-create life. Literally hundreds of definitions of what it should look like now exist, but none has yet emerged as an obvious winner. Coronaviruses have altered the course of history, and yet many scientists maintain they are not alive. Chemists are creating droplets that can swarm, sense their environment, and multiply. Have they made life in the lab? Whether he is handling pythons in Alabama or searching for hibernating bats in the Adirondacks, Zimmer revels in astounding examples of life at its most bizarre. He tries his own hand at evolving life in a test tube, with unnerving results. Charting the obsession with Dr. Frankenstein's monster and how the world briefly believed that radium was the source of all life, Zimmer leads us into the labs and minds of humans engineering life from scratch.