In our daily lives, the rule of law matters more than anything and yet remains an invisible presence. We trust in the rule of law to protect us from governmental overreach, mafia godfathers, or the will of the majority. We take the rule of law for granted, often failing to recognize its demise -- until it is too late. For under attack it is, not only in the growing number of authoritarian countries around the world but in Europe, too. As a citizens guide, this book explains in plain language what the rule of law is, why it matters, and why we have to defend it. The starting point is to ask why EU efforts to promote the rule of law in candidate countries have succeeded or failed, and what this tells us about what is happening inside the EU. The authors move on to suggest ways of strengthening the rule of law in Europe and beyond. This book is a call to action in defence of the most precious human invention of all time.