There is a certain large country in the central plains of the mainland ruled by an emperor. In that emperor's harem young women are often sold to work there for a set period, in some cases these maids are kidnapped and sold there by strangers. One such case, Maomao, an apothecary from the pleasure quarters, being plain and reluctant, attempts to keep a low profile until her term of service is complete. She has no desire or interest to become an important individual in the inner palace and would much rather be mixing medicines, dealing with poisons, or experimenting (with herself as the most convenient lab rat). However, there is a rumour that the emperor's children are being cursed to death; ever skeptical and inquisitive, Maomao cannot resist a little well-intended investigation, and catches the attention of a mysterious high ranking official, among others. Thus her peculiar career as an apothecary-cum-poison-tester begins.