The shoot in Eastern Europe must have been tough, but however much one might sympathize with the difficulties, Larysa Kondracki’s “The Whistleblower” comes off as an earnest but sluggish tale of corruption in the aftermath of the Bosnian war. Rachel Weisz works diligently to make the well-meaning but dour fact-based movie compelling, but it comes off as slack instead.

Certainly the fact-based subject matter is important. Weisz plays Kathryn Bolkovac, a Nebraska cop who was hired by DynCorp, a company hired after the Camp David accords in conjunction with United Nations efforts to train local police officers for duty in Bosnia-Herzegovina, where ethnic and religious divisions—as well as lingering animosities from the long, drawn-out conflict—threatened the fragile peace. (The company’s name, of course, is changed for legal reasons.) Having taken the job in order to accumulate the money she needs to move to Florida, where her children have been taken by her ex-husband, she still arrives in Sarajevo with the belief that she’ll be engaged in a noble cause.

That’s why she’s shocked when she comes to realize not only that most of the men she’s training are driven not by a sense of justice but by ethnic and gender prejudices, but that many of them—and members of her own training force as well—are implicated in sex trafficking that effectively involves the kidnapping and forced servitude of local girls. But when she tries to intervene and informs her superiors of what’s happening, she finds them unresponsive or, worse, involved themselves. Her only allies are a UN official concerned with women’s issues (Vanessa Redgrave) and an Internal Affairs investigator (David Strathairn), but they’re incapable of seeing that action is taken against the wrongdoers or even protecting Kathryn (or keeping her from being fired).

Weisz gives Bolkovac a gritty determination throughout, and Redgrave and Strathairn both do their usual reliable jobs, but otherwise the film stumbles along. In order to personalize the horrors being perpetrated against the victims of the sex ring, the script by Kondracki and Eilis Kirwan focuses on one girl, Raya (Roxana Condurache), who leaves home after a dispute with her mother and is sucked into the scheme. The narrative effectively becomes the story of Bolkovac’s efforts to rescue her and return her to her family, though she’s stymied at every turn by colleagues who are either corrupt or ineffectual. Unfortunately this section of the picture is so fragmented and incomplete that it doesn’t register as powerfully as it should, though a revelation near the close about who was responsible for the girl’s virtual abduction has genuine impact. And the portrayal of those on the other side—the American trainers and company officials, UN bigwigs hamstrung by regulations or more anxious about preserving the institutional reputation than doing the right thing, most of the Bosnian policemen—lacks nuance. In that context the introduction of a solitary local cop who tries to take Bolkovac’s injunctions about following the rule of law to heart comes across as a half-hearted gesture.

One has to respect “The Whistleblower” for its attempt to bring a sordid reality to the attention of the wider public. And the outcome, disclosed as usual in some printed cards before the final credits, hardly demonstrates the triumph of justice. But despite the dedication of Weisz, Strathairn and Redgrave, it’s a stolidly didactic piece that happily eschews the slickness of similarly-structured Hollywood flicks like “Norma Rae” and “Erin Brockovich” but, despite the authentic look of the locales, doesn’t manage to make the story as gripping as it should be.