Rachel Weisz has her best role since her Oscar winning turn in “The Constant Gardener” in “The Whistleblower,” another tale in which she plays an idealistic, morally complicated woman in pursuit of a deadly truth.

This “inspired by a true story” film is an account of Nebraska cop Kathryn Bolkovac’s service as a UN contracted peacekeeper in Bosnia in the late 1990s. A divorced mother who cannot find a way to transfer out of state to be nearer her teenage daughter, she took a job with a security contractor for big pay and a short tour in the Balkans. As she listens to the pep talk on arrival, you can sense in her the feeling that she’s there to do good, to “protect the rule of law where lawlessness is rampant.”

The ethnic strife isn’t beneath the surface, there. It’s right out in the open, local cops refusing to investigate domestic violence cases, especially those involving Muslims. Kathryn makes her mark by insisting that they start. She is promoted, put in charge of “gender affairs” by a UN official (Vanessa Redgrave) who gives her some autonomy, but not enough.

That’s what Kathryn finds out when she stumbles into a sex trafficking scandal that has all the signs of UN complicity. First-time feature-director Larysa Kondracki has started her film with the tricking of girls in the Ukraine, teenagers, who think they’re headed to a better life, only to wind up imprisoned in a dank bar in the Balkans, tortured and raped by paying customers. Kathryn meets a few of them, and one, Raya  (Roxana Condurache) she promises to protect and serve. She sees something of her own child in this 15 year old, and much of the film is her furious effort to get around bureaucrats (Monica Belucci) and armed, menacing peace keepers who want to keep her from breaking “policy.”

“I’m an American police officer,” she declares. No matter who I work for, I wouldn’t let somebody get away with this.”

David Strathairn is the rare American in this cast of mostly-Brits playing Americans, and he stands out as an internal affairs officer who seems to be one person willing to listen to Kathryn’s charges and to help her find her way through the byzantine UN immunity rules and local laws.

Kathryn isn’t a super cop and we see the diminutive Weisz do nothing physically that would defy the laws of physics.

The “enemy” here is a trifle ill-defined, and the actual police work Kathryn does is shortchanged — simple shots of her adding photos and snippets of evidence to the massive bulletin board where she tracks the case have to suffice. And there’s more than a hint of melodrama to the possible romantic entanglements and references to the daughter she left behind in the states.
But “The Whistleblower” is still a first-rate one-woman-against-the-system drama, a film benefiting from grim recreations of an ugly reality and a stellar cast determined to expose it.

MPAA Rating:R for disturbing violent content including a brutal sexual assault, graphic nudity and language

Cast: Rachel Weisz, Vanessa Redgrave, David Straithairn, Benedict Cumberbatch
Credits: Directed by Larysa Kondracki, written by Kondracki and Eilis Kirwan. A Samuel Goldwyn release.

Running time: 1:48