Zhang Guilan, 60, has been a widow for years, and loneliness has become her most familiar companion. Her busy children, unable to spare time to care for her, hire a nanny named Liu Mei—who, beneath a loyal facade, is a gambling addict driven by greed. Liu Mei subjects Zhang Guilan to water and food deprivation, beatings, and other abuse, hoping to seize her money to pay off gambling debts. Frail and kept under strict watch, Zhang Guilan's repeated cries for help are covered up by Liu Mei. Though her children Li Wei and Li Juan sense something wrong with their mother, they are repeatedly put off by Liu Mei amid their own daily distractions. In the end, the two discover the truth, gather evidence through surveillance cameras, and after many twists and turns finally expose Liu Mei's crimes, bringing her and her accomplices to justice.