Medical student Jiang Yuanyue, in search of her missing elder sister Jiang Shuwan, assumes the alias Yan Ran and deliberately approaches Zeng Yuankai, the second young master of the Zeng family. Successfully infiltrating the household by posing as Yuankai's maid, Yan Ran continues her investigation and ultimately discovers her sister's body buried in the abandoned courtyard of the Zeng estate. She comes to suspect that the culprits may be the two Zeng brothers. Following the mysterious death of Chen Shulin, Yan Ran and Zeng Yuankai gradually uncover the true, ruthless nature of the Zeng family patriarch Zeng Shaozong. They expose his past crimes, including the deaths of Jiang Yunwen and Gu Manqing, Zeng Yuankai's biological mother, and the devastating truth that Zeng Shaozong is not Yuankai's real father.