The Earth must make way for a galactic hyperspace bypass. Thus begins the famous story by Douglas Adams, "The Hitchhiker's Guide to the Galaxy." You don't need to be familiar with it to understand this book. However, Nicole Deitelhoff and Michael Zürn use it as a starting point to navigate through the complex history and theoretical landscape of International Relations with a sense of adventure and enjoyment. They present the subject as a galaxy populated by a variety of planets, each housing different civilizations commonly known as schools of thought and individual theories, which are each embedded in specific historical contexts. Given such a sometimes overwhelming complexity, the authors orient themselves in their engaging and informative textbook around the well-known fundamental principle.