Poisoning is as old as humanity itself. In ancient Rome, emperors frequently resorted to poison to eliminate unwanted rivals. During the Renaissance, dinner guests were often dispatched with poisoned wine. In modern times, sinister figures employ treacherous poisons in their attempts to commit the perfect murder, substances that are nearly impossible to detect. These methods are the result of a long series of experiments, as the same substances that can kill or make people ill have also been consumed throughout history as narcotics, aphrodisiacs, and even life elixirs. For as every amateur toxicologist knows: it is the dose that makes the poison. This chronicle documents the most historically notable deaths by poison. It tells the thrilling stories of the murderers, addicts, and victims of these mysterious substances—from Cleopatra, the Borgias, and Qin Shihuangdi to the secret agents and terrorists of today. The origins, effects, and deadly power of the most common poisons from each historical era are presented, along with the methods by which power-hungry, dangerous, and desperate figures in history misused these substances for their own ends.