In 1928, Los Angeles, single mother Christine Collins (Angelina Jolie) returns from work to find her nine-year-old son Walter (Gattlin Griffith) gone and calls the L.A.P.D. to initiate a search. Five months later, a boy is found in Illinois who fits the description, and he says he's her son. To fanfare and photos, the L.A.P.D. reunite mother and son, but she insists he's not her son. The cops dismiss her as either a liar or hysterical. When she joins a minister in his public criticism of the police, they in turn use government power to intimidate and silence her. Meanwhile, an officer goes to a dilapidated ranch to find a Canadian lad who's without legal status; the youth tells a grisly tale. There's redress for murder; is there redress for abuse of power?—
After Christine's son goes missing, she reaches out to the LAPD to find him. But when they try to pass off an impostor as her son to quieten public protests, she refuses to accept him or give up hope.