After becoming pregnant, Caihe, a maid in the He household, moves into the East Courtyard. Taking advantage of He Wenchang's constant indulgence, she gradually begins interfering in household affairs, competing for servants, and repeatedly testing the limits of Lin Jingyi, the principal wife. After an unexpected incident, Caihe shifts the blame onto Lin Jingyi, but an old prescription and past events bring the painful truth of ten years ago to light. Faced with misunderstandings and growing disorder, Lin Jingyi finally refuses to give in any longer, making He Wenchang realize that a truly harmonious family can never exist without boundaries and rules.