The setting of the book is set in 1952 and the family has been required to move from Los Angeles to London. The main character is Janie, a 14-year old girl who meets an apothecary's son. He also meets his son Benjamin Burrows. Soon afterwards, Benjamin's father is kidnapped and Jamie and Benjamin take on the task of searching for the apothecary. She and Benjamin find the apothecary's book and must figure out the mysteries of the book in order to find Ben's father. The book is called the Pharmacopeia. At the same time they are searching for his father, they are also trying to keep away from the enemies, Russian spies, who are trying to get the book as well. All along the way trying to find his father, and staying away from the Russian spies, Janie and Ben use recipes for the potions to try and save themselves, find Ben's father, and save themself from disaster.