This book deals with Design and Conspiracy Theories, two things that are often thought of as opposites. Design is generally perceived as something that simplifies and targets the essence of things; something that should say the Truth. Conspiracy theories instead are far-fetched and create confusion. Design is expected to be able to bypass false rhetorics because its very premise is to deal with how things work in reality. However, what is argued in this book is that design and conspiracy theories mirror each other. They act with similar goals and they adopt comparable representations. They intersect in their practices and in their artifacts because they share a common ground at their fundaments. This common ground is Conspiratorial Design.