Su Wanqing has worked tirelessly running the Zhou household for six years, yet her mother-in-law, Wu Guifen, has always treated her as an outsider. One morning at breakfast, only one of the fifteen steamed buns remains. Just as Su Wanqing reaches for it, her son An'an repeats his grandmother's words: "Mom is an outsider and isn't allowed to eat one." Those words finally shatter Su Wanqing's patience. She flips the table and demands a divorce, only to discover that her husband, Zhou Zhiyuan, has already set a trap. He has been lying about paying 8,000 yuan a month on the mortgage, when the money is actually being diverted to his mistress, He Jiawen, to purchase property. With help from her friend Tang Yue and Lawyer Cheng, Su Wanqing gradually traces the flow of funds and gathers evidence.