In eighteenth-century London, women whisper of a hidden apothecary shop and its mysterious owner, Nella, who sells well-disguised poisons to use against the oppressive men in their lives. Nella's dark world is no place for the newest patron, a precocious twelve-year-old named Eliza Fanning, but their unexpected bond sparks a string of consequences that echoes through the centuries.
Two hundred years later, aspiring historian Caroline Parcewell is running from her own demons when she discovers a clue to London's long-unsolved "apothecary murders." Caroline's upended present soon collides with an explosive history, binding her fate to Nella's and Eliza's in a stunning twist that transcends the barrier of time.