"The Poisoner's Handbook" is a non-fiction book by Deborah Blum that explores the history of forensic science in the early 20th century. It focuses on the development of toxicology and the role of the New York City medical examiner's office in solving crimes involving poison. The book highlights key figures, including Charles Norris, the first chief medical examiner, and Alexander Gettler, a pioneering toxicologist. The narrative intertwines true crime stories with scientific advancements, illustrating how poisons were used in murders and how forensic techniques evolved to detect them. It emphasizes the importance of understanding toxic substances in both criminal investigations and public health.