Shen Yanqiu, a funeral cosmetologist, discovers suspicious details on her older sister's body and becomes convinced that her brother-in-law, Lu Weizhou, is the murderer. Taking advantage of her profession, she gathers evidence from the deceased driver, company financial records, and other sources. At the seventh-day memorial ritual, she publicly confronts him, only to be driven out by her family. Facing threats and suspension from work, she carefully executes her plan, repeatedly using physical evidence to shatter Lu Weizhou's psychological defenses, determined to make him confess with his own mouth.