This book is an excursion into the drug development process, from the initial conception in a chemical or molecular biology lab, via tests in isolated cells and animals, to the stage of clinical trials. The human body is a complex ecosystem where little is conclusively known in terms of its response to medication, for both sick and healthy individuals. The considerable degree of uncertainty inherent in health-related research can lead to approval of controversial medicines, particularly in high-stakes scenarios and medical crises. Real-life examples are drawn on here to explain the decision making processes behind the acceptance of new drugs, disproving misconceptions around medicines by delving into the history and current practice of the drug development process.