The Perfect Poison

The Perfect Poison is a historical romance with a mystery in it, by the American writer Jayne Ann Krentz, published in 2009 and part of her Arcane Society series.

Lucinda Bromley is a botanist who lives on the edges of respectable society because of a rumour that she poisoned her fiance, and because of the talent that gave rise to it: she can detect almost any poison by taste or smell, which makes her useful to people investigating suspicious deaths and impossible for London to be easy about. When a lord is killed with a substance that includes a very rare fern taken from her conservatory a month earlier, she becomes the obvious person to blame, so she has to find out who took the plant. The Arcane Society books are set in a version of Victorian England where the society exists to study psychic talents, and this one combines the investigation with a courtship.

The society appears in the author's other historical novels as well, and its members are the people who look into what the ordinary authorities cannot.