For a significant portion of the movie­going public, the words “Judi Dench” are enough to send them straight to the closest theater where one of her films might be playing. And for good reason: At 78, the British actress has become an international treasure, able to play steely, formidable characters with as much ease as cozier, more grandmotherly roles.

All those qualities can be glimpsed in “Philomena,” in which Dench plays the title character, a woman who, as a pregnant teenager in 1950s Ireland, was forced to give her son up for adoption after giving birth to him in a Catholic abbey. As the soft-spoken, slightly frumpy Philomena Lee, Dench delivers one of her most recessive, unprepossessing performances yet; her dashing silver-haired turn as James Bond’s “M” is thoroughly banished beneath a staid crown of mousy curls. But that signature brand of Dench tungsten glints through, as Philomena embarks on a search for her now-middle-aged son and debates the tenets of her faith with the skeptical journalist chronicling her journey.

That ink-stained wretch, Martin Sixsmith, is winningly played by the British comic actor Steve Coogan, who has adapted Sixsmith’s book, “The Lost Child of Philomena Lee,” with a tone-perfect mix of acerbity and tenderness. As Martin and Philomena trundle along on a picaresque voyage that takes them from rural Ireland to Washington starting in 2004, his mordant asides — as often as not having to do with theology and organized religion — consistently fly over Philomena’s head.

But the modest, provincial Philomena, whose steadfast faith Martin condescendingly equates with her taste for lowbrow romance novels, tends to get the last word. After delivering a flustered soliloquy on whether he believes in God, Martin turns the question to Philomena. “Do you?” he asks her. “Yes,” she says simply. (Later, when Martin refers to something as “evil,” Philomena insists that she doesn’t like that word. “No, evil’s good, story-wise,” he reassures her.)

If Philomena’s devotion is admirable, the blind eye she turns to the nuns who took her child is less understandable, and Martin serves as a suitably outraged audience surrogate as he reacts to an appalling revelation midway through the film. The depredations of the abbeys where Philomena and her contemporaries were housed were searingly represented in Peter Mullan’s shattering 2002 drama, “The Magdalene Sisters.” Director Stephen Frears doesn’t revisit those horrors but examines their equally sadistic aftermath, in which human lives were commodified much like the religious relics sold in the abbey’s front vestibule.

When Philomena and Martin arrive in Washington, the film takes on fascinating added meaning, obliquely reminding the audience of an era when homosexuality was the stuff of closeted stigma, a time that may seem as antediluvian to some audience members as the shame of an unwed mother in the 1950s. (In this way, “Philomena” serves as an effective bookend to the equally moving “Dallas Buyers Club.”) But at its core, this clever, wrenching, profound story underscores the tenacity of faith in the face of unfathomable cruelty. Evil may be good, story-wise. But virtue, at its most tested and tempered, is even better.

★ ★ ★ ½

PG-13. At area theaters. Contains strong profanity, thematic elements and sexual references.
95 minutes.