Lucinda Bromley is a botanist living in Victorian London. She has an apparently paranormal knack for detecting poisons which makes her quite a useful friend to the police. But, in the past wrongly suspected of poisoning her fiancé, she senses peril when she discovers an aristocrat was done in by a poison made from a plant stolen from her conservatory. Lucinda is a member of the Arcane Society, dedicated to the study of paranormal phenomena, and she and fellow member Caleb Jones set out to solve the case. They fall head over heels for each other, as old Arcane Society secrets emerge and a knot of danger tightens around Lucinda.