Saoirse Ronan in Brooklyn (Kerry Brown/Fox Searchlight Pictures )

As I took my seat to watch Brooklyn at the New York Film Festival, the middle-aged man to my left flashed me a dirty look. Clearly the gentleman did not want company next to him, and so he made sure to throw me the kind of pitch-black shade that lets you know you’ve invaded a New Yorker’s space. Dude, I thought to myself. We’ve got a full house. Give me a break. As the lights went down I could feel him bristling with irritation by my side.

Halfway through the movie, I heard a wet snuffle. I turned to see my hard-boiled seatmate dissolving in tears. The young woman on my right was also wiping her eyes. And so, I realized, was I. The grumpiest of big-city fusspots would succumb to this wonderful film with its deep, openhearted emotional power.

Its story is simple. A young Irishwoman, Eilis Lacey (Saoirse Ronan), leaves her stifling 1950s hometown for a new life in New York City. Living with other single girls in a fusty Brooklyn boardinghouse, Eilis fights homesickness, learns to charm customers at her salesgirl job, and aims to improve her prospects by enrolling in night school. At a dance, she meets a young Italian-American man named Tony (Emory Cohen), whom she grows to love and trust. An unexpected tragedy brings her home, where her newly acquired polish and confidence attract another suitor. Where does Eilis’s loyalty lie: to her old home or to her new one?

Yearning runs through Brooklyn like a pulse. From the moment she sets foot on the boat, Eilis longs for her mother and sister and for her sense of place among them. They desperately miss Eilis, and their cherished, pined-for letters ring with unspoken sadness. When Eilis returns to Ireland, guilt and obligation to the ones she left behind, along with other more complicated emotions, will exert a pull she can barely resist.

But the movie overflows with happiness, too, glowing and invigorating. We see Eilis grow from shy country girl into someone prettier, more self-assured and increasingly comfortable deploying her considerable wit. Acts of kindness from a sympathetic priest (Jim Broadbent) and Eilis’s aloof but sharp-eyed boss (Jessica Paré, late of Mad Men) help propel the newcomer’s life in the right direction, and the love affair between Eilis and her beau Tony unfolds with tenderness, humor, and sexy chemistry between the two leads.

Eilis finds her way in an era that is utterly lost to us now, and it’s a measure of director John Crowley and writer Nick Hornby’s skill that the bygone world comes absorbingly alive. Dialogue is folksy, yet tart and biting—it helps keep the movie light. A standout comic scene where Eilis meets Tony’s Italian family over dinner is not only very funny but shows Eilis learning to move beyond her all-Irish enclave. Highlighted by artfully composed shots (imagine Edward Hopper in Technicolor), vivid period detail places the movie gracefully within its time frame.

But Brooklyn does not only romanticize the past. Excellently played and well-cast secondary characters, such as the busybody mistress of the boarding house (Julie Walters) and Eilis’s catty housemates, remind us how confining and small Brooklyn’s vanished world could be. One especially cruel gossipmonger in Eilis’s hometown would make any sane Irish lassie want to flee thousands of miles across the ocean. That character’s malice will introduce a dark current in a film that otherwise likes to portray people at their best.

Elevating a finely crafted work ares the delightful performances from Ronan and Cohen. Ronan blossoms before our eyes, but she never loses her grounding playing a young woman who, despite her decency, is no Pollyanna. We can see Ronan’s mind working—and heart breaking—as Eilis confronts her fateful choices. Cohen’s performance is almost too broad as blue-collar guy with a heart of gold. He makes up for it with well-paced hesitation, taking his time sizing up the best way to approach and win Eilis. Cohen will triumph over not just her but the ladies in the audience, and quite a few men, too.

Go and see Brooklyn. It has its flaws, and you’ll spot them, but it is strong, sure, true, and piercingly good. It will make you ache for all the people and places you’ve ever loved and had to leave.