In 1928 Los Angeles, a single mother, Christina Collins (Angelina Jolie), leaves for work on a Saturday, leaving her 9-year-old son at home without any supervision. Upon her return home that night, he has vanished without a trace. Five months later, the LAPD inform her they've found her son in the Midwest and he's on his way home. Regrettably, the boy isn't her son, though the police refuse to believe her and are convinced she's just in shock. Driven by her quest for the truth, she exposes corruption in the LAPD and captivates the people of Los Angeles with her horrific tale.