One week ago, Lin Mian, who was studying abroad in Germany, received a wedding invitation from her sister, Lin Qian. Just as she was about to pack her bags and return home, she was struck by the news of her sister's suicide. Lin Mian refused to believe that her strong and optimistic sister would take her own life, and the sudden decision to get married raised many doubts. As a result, Lin Mian set her sights on her sister's fiancé, Zhou Gongyu. Disguising her identity, Lin Mian returned to China and arrived at the Zhou family's private manor, where her sister had taken her life, to begin her investigation.