Set in a fictional imperial China-inspired land, the series follows Maomao, a young woman trained in the art of herbal medicine and toxicology who is kidnapped and sold into indentured servitude as a low-level maid in the inner palace. Possessing a sharp intellect, a cynical outlook, and an eccentric obsession with poisons and medicine, she tries to keep her head down until her curiosity is piqued by the mysterious illnesses plaguing the Emperor's heirs. After leaving an anonymous, clever warning that saves the royal babies, her medical knowledge is discovered by the dashing and influential eunuch strategist, Jinshi. Promoted to a food taster and investigator, Maomao finds herself increasingly entangled in the dangerous political conspiracies, court intrigue, and medical mysteries of the imperial harem.