Set in a fictional imperial court inspired by ancient China, the story follows Maomao, a young woman trained in the art of herbal medicine and toxicology. After being kidnapped and sold into indentured servitude at the imperial palace, she attempts to keep a low profile until her term is up. However, her insatiable curiosity and medical expertise are piqued when the Emperor's infant children fall mysteriously ill. She leaves anonymous clues to save them, catching the attention of Jinshi, an influential and strikingly handsome eunuch who quickly recognizes her unique talents and promotes her to serve as a food taster and investigator of palace poisons and mysteries.