The Yong'an Marquis's mansion is a vast and stifling place, ruled by rigid customs. When Qinghe, a third-class maid, is suddenly assigned as heir Xiao Jue's concubine, she has no family connections to rely on and no ambitions to climb the social ladder. All she wants is to make a quiet life for herself amid the open and hidden dangers.
Cautious and dutiful, she refuses to compete for favor and even asks to take contraceptive medicine, yet she cannot escape the schemes in the household. A jealous maid trips her up, while the second young master, Xiao Heng, covets the heir's position and uses her to frame Xiao Jue. The Lady Liu feigns closeness while hiding her own motives. Even the heir's wife, Qin Wanrou, who enters the mansion by imperial decree, grows jealous and makes life miserable for Qinghe, intent on killing her.
In this treacherous battle within the household, Qinghe sheds her timidity and sees through the schemes swirling around her. Her keen eye for detail helps her protect herself, and grateful for Xiao Jue's care, she risks her life several times to help him out of danger. At first, the cold and reserved heir sees her only as a capable subordinate. But after watching her care for him day and night when he falls ill, and remain by his side even when she is imprisoned, his heart begins to soften. He rebukes his wife for her sake and rescues Qinghe from certain death all alone. He even refuses the emperor's spoken order to marry, choosing to cherish Qinghe alone.
A conspiracy to usurp the throne plunges the marquis's household into chaos. Qinghe searches for evidence and reunites with former allies to help Xiao Jue clear his name, and the two pledge themselves to each other in the face of death. Once the villains are brought to justice and the household's power structure is reshaped, Qinghe earns the old madam's respect through her character and abilities. She takes charge of the heir's household, rising step by step from a lowly concubine to the woman dearest to his heart.
When she becomes pregnant, she is made a secondary consort and bears children. After Xiao Jue inherits the title of marquis, she becomes the Marchioness. The maid who once languished in the dust at last wins the marquis's exclusive devotion, living in blissful comfort, year after peaceful year.
