This fourth and final volume mainly continues where Volume III left off. This book continues to explore the areas the inquisition had influence and the way it found out how heretics emerged and worked in the respective fields the inquisition caught them in. Although the methods were brutal and the victims often innocent, the inquisition shows how thorough it was when dealing with these "sins." And then finally, Lea shows us the steady decline of the inquisition after the wars of Napoleon and how they tried to survive but failed.