“TERRIBLE injustices are happening all the time,” the actress Rachel Weisz said, “but only some of them make it to the screen.”

And most of those arrive in documentary form these days. The few features with a message that do make it to theaters often have a single individual at their center, like Karen Silkwood or Erin Brockovich, or a pair, like Bob Woodward and Carl Bernstein, ordinary people in extraordinary circumstances who become the audience’s guide through a murky subculture.

Add Kathryn Bolkovac, an American police officer, to that list. She is portrayed by Ms. Weisz in the new film “The Whistleblower,” opening Friday. It follows Ms. Bolkovac’s real-life assignment as a United Nations peacekeeper in Bosnia in the 1990s, a job that exposed her to a world of international workers complicit in and in many cases fostering the international trade of young women for sex. Ms. Bolkovac’s investigation led to her firing.

“There were so many people in the same situation as her,” Ms. Weisz said. “They saw what was going on, and they didn’t respond in the way that she did.”

Her crusade, which was widely covered by the European press after she filed (and won) a lawsuit in Britain for wrongful dismissal, drew Ms. Weisz, who in turn hopes to attract audiences in a season when Hollywood’s prime concern seems to be the plight of superheroes and young wizards.

International sex trafficking has figured in the plots of the Liam Neeson film “Taken” (2009) and countless episodes of the television series “24” and “Law & Order,” but such narratives tend to present the victims as a mass of nameless women and its perpetrators as foreign deviants. “The Whistleblower,” which makes one of the victims a crucial character and uses graphic scenes of abuse, implicates the United Nations, the State Department, private contractors and nongovernmental organizations in the sex trade.

Ms. Kondracki agrees. “There’s a bigger goal, and that is information and exposure.” Sex trafficking continues, she added, because “no one is putting pressure on governments to stop it, and there is no accountability. It’s laziness.”

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