There have been many movies about the experience of Irish immigrants to the United States, period and modern, good (“In America”) and bad (“Far And Away”). John Crowley’s adaptation of Colm Toibin’s 2009 novel, scripted by Nick Hornby, is one of the more agreeable ones: it’s hardly subtle or incisive, but works as an old-fashioned tearjerker bolstered by a strong lead turn from Saoirse Ronan.

Ronan plays Eilis Lacey, whose life with her mother (Jane Brennan) and older sister Rose (Fiona Glascott) in small-town 1951 Ireland is without much promise. A shy, physically unremarkable lass, she’s overlooked by the young men of the place, who gravitate toward her prettier pal Nancy (Eileen O’Higgins), and mistreated by her part-time employer Miss Kelly (Brid Brennan), a nasty-tongued shop owner. Concerned for her sister’s future, Rose arranges with the church to sponsor Eilis’ immigration to America, and after a difficult Atlantic crossing—during which a sophisticated cabin mate (Eva Birthistle) offers her some sage advice—she arrives in Brooklyn, where kindly Father Flood (Jim Broadbent) has arranged a place at the boarding housed run by Mrs. Keough (Julie Walters) and a job at a high-end department store, where a primly officious floor manager (Jessica Pare) helps her adjust.

But her intense homesickness remains until, at a parish dance, Eilis meets Tony Fiorello (Emory Cohen), a young Italian man—a plumber by trade—who immediately falls for her. They have a sweet courtship that includes going out to movies like “Singin’ in the Rain” and having dinner with Tony’s large family, and are becoming increasingly serious when Eilis gets a call from home that requires her returning to Ireland. Before she goes, however, Tony asks her to marry him, and they’re quickly hitched in a quiet civil ceremony.

Back in County Wexford, however, Eilis, who’s blossomed during her American stay, finds herself treated much differently. Finding it difficult to tell anyone that she’s married, she’s pressured by her mother not to go back to New York, wooed by eligible bachelor Jim Farrell (Domhnall Gleeson) and offered a permanent job with a local firm. In the midst of all the attention she finds her commitment to Tony fraying, and actually contemplates remaining until an encounter with an old nemesis makes up her mind for her.

That encounter is, in fact, one of the most glaring flaws in the narrative: it’s based on a coincidence so enormous that while one might be willing to swallow it on the page, when transferred to the screen its implausibility is undeniable. But there’s a larger problem. We’re meant to sympathize with Eilis’ mixed feelings about returning to Brooklyn or remaining in Ireland. But the fact is that she’s now a woman married to a wonderful man, and her reluctance to tell people that and instead effectively pretend that she’s still unwed—leading on poor Jim in the process—comes off as not a little selfish and unfeeling. You might, in fact, feel a bit of squeamishness in watching her go about as though she had no commitments to anyone but herself.

Still, Ronan is so luminous in her transformation from wallflower to fully blossomed young woman that you’re likely to set aside your reservations about Eilis’ actions. Playing a character about as far removed as one could imagine from her turn in Joe Wright’s “Hanna,” she demonstrates not only her versatility but, once again, her on-screen charisma. Just as impressive is the work of relative newcomer Cohen, who brings to Tony a mix of bravado, insecurity, gentleness and longing that’s extraordinarily touching. The supporting players are aces across the board, from Broadbent’s avuncular priest and Walter’s hilariously peremptory landlady to Gleeson’s gentlemanly suitor and Brennan’s miserable gossip. The picture is also beautifully made, with Francois Saguin’s production design capturing—indeed exaggerating—the ripe colors of both an Irish backwater and fifties Brooklyn—and Odile Dicks-Mireaux contributing a succession of spot-on costumes, all caught in lovely widescreen visuals by cinematographer Yves Belanger. Crowley, who directed the powerful “Boy A” and the exuberant “intermission” before stumbling with the mawkish “Is Anybody There?” and the staid thriller “Closed Circuit,” segues into this film’s sentimental nostalgia quite successfully.

“Brooklyn” is unabashedly a woman’s picture of the old school, but when it’s done up as well as here, it’s worth going back to class.