Arsenic, known since antiquity as the ‘king of poisons’, gained infamy among nobility and the bourgeoisie as a public menace. Synonymous with crimes of ‘fashion’, arsenic poisoning was the silent killer and a nearly untraceable means of murder. It wasn’t until early 19th century France that the poudre de succession met its match, ushering in a revolution in forensic toxicology with the ‘chief terror of poisoners’.