Beginning as a symptomatic reading of Arthur Conan Doyle’s use of a fictional African root poison, the Radix pedis diaboli, in “The Adventure of the Devil’s Foot” (1907), and Indian poisoned darts in The Sign of the Four (1890), this article makes some general comments on the history of colonial tropical toxicology, focusing on the Indian aconite (Aconitum ferox) and its roots (Radix aconiti indica). Arguably, Doyle had aconite in his mind while creating the fictional African root poison. Victorian toxicologists, who were deeply interested in Indian poisons, created stereotypes of India as congeries of melancholy and culturally backward, industrially primitive, and morally corrupt societies. Doyle’s fictional poisons were influenced by a normative cultural bias that saw tropical pharmakons like aconite with an Orientalizing gaze. By shifting the geographical focus from Doyle’s “Ubangi country” to nineteenth-century India, I draw attention to a larger spectrum of tropical toxicology. The colonial zeal to taxonomize the properties and utility of tropical pharmakons obsessively revolved around their toxic uses as criminal weapons or accidental killers, while marginalizing the medicinal uses that the plant had been historically put to by ancient Indian physicians.