The title pretty much provides the perfect description for Stephen Bradley’s uplifting biographical film about Christina Noble, an Irish woman who overcame a hardscrabble childhood and difficult life to establish a string of centers to aid impoverished and homeless children in Vietnam and Mongolia. Inevitably the shadow of a public service announcement hangs over any such story, but as portrayed at various stages by three actresses, Noble proves a sufficiently pugnacious character to overcome most of the sanctimoniousness that often afflicts such tales of self-sacrifice.

Born in Dublin at the tail end of World War II, young Christina (played by Gloria Cramer Curtis) suffers from extreme poverty, literally singing in the streets for her supper, and when her mother dies and her alcoholic, volatile father (Liam Cunningham) proves unable to raise her and her siblings, the children are separated and shipped off to foster care, with Christina winding up in a rural Catholic institution run by some very strict nuns. When she reaches the age for release (and now played by Sarah Greene), she reunites briefly with her father in Dublin. He immediately takes advantage of her again, and shortly afterward she’s brutally raped by street thugs. Taken in by nuns once again, she gives birth to a son, who’s immediately put up for adoption without her consent.

Fortunately she’s invited by an old school friend, Joan (Ruth Negga), to join her in Birmingham, where she takes a job at a fish and chips shop and meets Mario (David Mumeni), whom she soon weds. Unfortunately he soon turns reckless and abusive toward her and their children, and so she leaves him to raise the kids on her own.

This chronology of Noble’s early life is interrupted, however, by sequences of her (now played by Deirdre O’Kane) arriving in Vietnam in 1989, sent on a mission of mercy by dreams about the street children of that land. Taking an immediate interest in the kids, who are dismissed by locals as “bui doi,” or “like dirt,” she joins forces with Madame Linh (Nhu Quynh Nguyen), the dedicated director of an orphanage, and persuades authorities to grant her a three-month work permit to secure financial support to renovate an unused part of the orphanage for her dream of a facility to house the homeless children. With the ninety-day deadline fast approaching, she anxiously awaits word of whether Jerry (Brendan Coyle), an oil executive she’s approached, will convince his board to subsidize the project. In the meantime, she also takes steps to see to it that the authorities intervene against David Somers (Mark Huberman), a foreigner who picks up street children to satisfy his appetites.

It’s a foregone conclusion that matters will work out in Christina’s favor, of course—the string of shelters she’s managed to establish under the aegis of a foundation named after her makes that inevitable, and one must wonder whether her last-minute success in avoiding deportation has been amped up by Bradley for dramatic effect. Whether or not that’s the case, however, her story certainly earns the triumphal spirit with which the picture closes, even though the footage of the actual Noble accompanied by many of the children she’s helping has an almost obligatory feel.

It can’t be said that Bradley’s film is especially well structured—the lurches from 1989 to the past and back again aren’t handled as fluidly by the director and editor Mags Arnold as one imagines they might have been. But the idea behind them is a good one, surely preferable to a straight chronological treatment. And the film benefits from solid work on the part of the rest of the crew, including production designer Cristina Casali and costume designer Charlotte Walter, whose work in the period scenes of the fifties and sixties is especially fine. The Vietnamese location sequences are ably done as well.

Much of the film’s success, however, is due to the cast, not least O’Kane, Greene and Curtis, who together make Christina a credibly take-charge person at each stage of her life and make the audience care about her, even though we may know her history. Among the other actors Nguyen stands out as a woman of equal determination who, however, demonstrates it in a more restrained fashion, and fans of “Downton Abbey” will enjoy seeing Mr. Bates—that is, Coyle—in a somewhat more animated turn.

As the title indicates, this is a straight-up inspirational tale, but its sincerity and above-average execution set it apart from many other similar movies.