In the quiet corners of libraries, rare book rooms, and private collections, a few volumes hide a strange and unsettling secret. These innocent-looking, often beautiful books were bound with pigments so toxic they still pose a risk more than a century later. What was once considered tasteful design has become something closer to hazardous material. In this article, we're diving into the eerie history of arsenic-laced books—how they came to be, why they were so popular, and the modern-day conservators trying to track them down. Let's go!