Clint Eastwood’s Changeling recalls a time before DNA testing and the scrupulous enforcement of due process in late-’20s Los Angeles, when corrupt police presided over the city with something close to impunity. Consider the strange ordeal of Christine Collins.

A single mother living in the Hollywood suburbs, Collins returns from work one night to discover that her nine-year-old son has gone missing. She files a report and waits anxiously until some months later when a handsome, cocksure police captain (Jeffrey Donovan, of TV’s Burn Notice) struts into her office with the good news: Her son is alive and ready to come home. What he fails to realize, and later refuses to accept, is that the boy is not Walter Collins.

How could it happen? Were there no pictures of the boy, no distinguishing medical records? There were, we learn, but the police, reeling from the bad press incurred by rogue chief James Davis, were loath to admit that a rare, well-publicized triumph was in fact a hoax, perpetrated by a young runaway from Des Moines. On the orders of the captain, for whom challenging Christine’s sanity becomes a matter of policy, the investigation into the disappearance of Walter Collins is suspended. Mission accomplished.

Christine is devastated but not defeated. At the urging of Gustav Briegleb (John Malkovich), a reform-minded minister who uses her case to embarrass the police, she goes to the newspapers. She earns a state-sponsored trip to the psych ward for her troubles, but when a mass grave of missing children is discovered in nearby Riverside at the now-infamous Northcott ranch, the scales of justice begin to tip in her favor.

Eastwood, whose second career as a director has been distinguished by projects that reflect his passions for jazz, the Wild West and recent American history, is clearly connected to this material, a point he hammered home recently by advocating the death penalty for those convicted in child abduction and murder cases. Changeling was inspired by the true stories of Christine Collins and Gordon Stewart Northcott, the serial killer ultimately suspected in her son’s disappearance.

Northcott was executed in 1930, and Eastwood recreates his hanging here as a sort of public service. We see the monster and wince at the carnage left in his wake, and so, I guess, we have earned the cathartic privilege of watching him die. The scene feels unnecessary, though, a voyeuristic concession Eastwood might have judiciously omitted from a coda that already seems bloated with superfluous detail.

There is considerable anguish in his storytelling, and an almost palpable sense of moral outrage – understandable, given the indignities Christine Collins was made to suffer. This isn’t just a movie about a mother losing her child, it’s about a woman stripped of her civil rights and marginalized by the chauvinistic bullies who define the law. Eastwood addresses both aspects of the story, though it is Christine’s courtroom victory over the police that resonates most powerfully.

No satisfaction can be taken from the still-unsolved case of Walter Collins, whose body was never found. Played by Angelina Jolie, Christine moves from weepy desperation to righteous indignation as the hunt for her son leads her into the darkest recesses of the human soul.

Jolie’s performance is mostly one-note in the early going, but I suppose that comes with the territory when playing a character defined almost exclusively by grief. It’s not until the circumstances of her son’s disappearance begin to emerge, followed by the degradations she endures, that her story begins to gain traction and she summons the strength to confront her tormentors. Only then does Eastwood find his footing, as if energized by his desire to exact a measure of justice.