A forgotten story, an underground network of women, a deadly legacy of revenge.

Welcome to the secret apothecary. Hidden in the depths of 18th century London, it carries out some very special orders for its clientele. Women from all over the city whisper about a mysterious woman, Nella, who sells well-hidden poisons for them to use against their oppressive husbands. But Nella's dark world will start to be endangered when her youngest client, twelve-year-old Eliza, makes a fatal mistake.

Two hundred years later, aspiring historian Caroline Parcewell discovers an ancient apothecary bottle in the Thames and seizes the opportunity to investigate its origin in an effort to forget the horrific betrayal of her unfaithful husband. But when she uncovers the connection between the bottle and the unsolved murders of the apothecary throughout the centuries, Caroline's tumultuous present collides with an explosive story that intertwines her fate with that of Nella and Eliza, taking an unexpected turn that transcends the barrier of time.

The book has been translated into 40 languages and will be adapted into a television series by Fox.