SELF REFLECTION: Ashima (played by Tabu) and her husband must adjust to the cultural practices of the United States in The Namesake. Credit: Fox Searchlight Pictures

SELF REFLECTION: Ashima (played by Tabu) and her husband must adjust to the cultural practices of the United States in The Namesake. Credit: Fox Searchlight Pictures

There's no way to wrap your head around the enormity of India, so Mira Nair's new movie simply hurls us into it from the outset. Opening in a sea of flesh, The Namesake deposits us in the middle of a crowd surging through a Calcutta train station, an enclosed space where we're struck by a human density rarely experienced even in the largest American cities.

The mass of bodies soon segues into more manageable and even intimate exchanges, but the movie's sense of scale remains impressive — a family saga spanning two generations, The Namesake is nothing if not epic — and the train station imagery remains central to what it's all about. One of the main characters here has a life-changing experience on a train, but even more to the point, The Namesake is all about the intricacies of traveling between worlds, of packing up one's life and moving from one place to another.

The principal bodies in motion here are Ashoke Ganguli (Irfan Khan) and his wife Ashima (Tabu), a traditional Bengali couple who make a move to the United States and wind up living there as hyphenate-Americans, one foot in the old world and one foot in the new. We follow the Gangulis over the course of three decades and numerous changes, first meeting them as shy newlyweds in 1977 Calcutta, a time and place that director Nair paints with an eye for detail and an energizing passion unseen since Salaam Bombay, her powerhouse 1988 debut.

"Don't forget the old," advises Mama Gungali on the eve of the young couple's journey to the West, and one cut later the warm, vibrant colors of India have been replaced by an empty, grey apartment somewhere in the frozen expanses of upstate New York. The bitter Northeastern winter has its upside, though — water can be drunk straight from the tap, explains Ashoke to his astonished bride, no need to even boil it first! Even more amazing is the Bengali husband's offer to let his jetlagged wife lie down while he serves her tea. "It's the American way," he says with a smile.

Adapting Jhumpa Lahiri's 2003 bestseller in fine, cinematic style, Nair chronicles the Gangulis' changing lifestyles and attitudes over the years, detailing their trials and transformations with affection and rare intelligence. (And yes, it does turn out that the more things change, the more they stay the same, but you probably already knew that.)

Working on a canvas both microscopic and monumental, Nair slyly delineates subtle nuances in her characters and in their trajectories, deftly shifting the focus from one person to the next while contrasting specific cultural bugaboos that illuminate larger truths about the American emigrant experience.

If the whole thing sounds a bit overstuffed or even fussy, think again. Nair never preaches, always manages to entertain and orchestrates the material gracefully but loosely, giving the film a fluid, episodic feel that's mainly concerned with rooting around in the everyday textures of life. Time passes, bigger houses are acquired, babies are born — beginning with the curiously named Gogol, the male heir who will eventually become the focus of the film — and The Namesake unfolds in its own sweet time, giving us plenty to ponder even as it goes down ever so easy.

In its own quiet, unassuming way, the first 45 minutes or so of The Namesake is pretty sublime stuff (condensing long years into cinematic poetry with a sub-Asian flavor, it even earns comparison to Satyajit Ray's masterful Apu trilogy) — but the film begins to flounder a bit at the halfway mark, when the focus shifts to Ashoke and Ashima's son, Gogol (played with unexpected delicacy by Kal Penn, believe it or not, of Harold and Kumar notoriety).

The movie jumps ahead to 1998, where we discover that Gogol Ganguli — surely the best fictitious handle since Humbert Humbert — is now a pot-smoking, headbanging, thoroughly assimilated American youth, basically happy and well-adjusted, but more than a little ticked-off at being named after some weird, long-dead Russian writer.

Another quick cut pushes the film forward several more years, and Nair gives us Gogol — now known as Nick — as a rising young architect, living the good life on Manhattan's Upper East Side and hooked up with a thoroughbred WASP princess who's the very antithesis of the nice Bengali girl he's expected to marry.

Nair begins to lose control of the all-important rhythms of her film at this point, as the story begins to push in more conventional directions, making far too big a fuss over fairly unremarkable plot twists involving Gogol/Nick's confusion and borderline embarrassment over his cultural identity. The father and son butt heads at regular intervals, the characters experience loss, grief, make radical lifestyle changes, discuss Joseph Campbell, find love, lose it and find it again.

Events begin piling up and the film occasionally skirts the edges of big, fat melodrama, but even at its soapiest there are more than enough grace notes to redeem The Namesake and keep it on track. The film signals the death of a loved one not with hysterics or charged exposition, but by simply observing the deceased's significant other slowly walking through their shared home in the middle of the night and methodically turning on every light in the house.

And when the funeral takes place, a brief glimpse of a blonde girl in black among a crowd of white-clad mourners (the traditional Hindi mourning color) says more than reams of overheated dialogue between emigrant parents and their assimilated American children.

And through it all, everyone in Nair's movie keeps moving, keeps changing. A terrible tragedy takes place on a train at the outset of The Namesake — the movie assaults us with it almost immediately but doesn't fully explain its meaning until nearly an hour in — but preceding that tragedy are two strangers on a train casually conversing about the pleasures of, among other things, travel.

That's really the key idea here, and The Namesake, for the most part, communicates it beautifully. Despite the potential for disaster, the film seems to say, what makes us fully human is the desire to remain in motion. And to experience the world, as The Namesake would have it, is to throw ourselves into an amazing journey that almost inevitably brings us back to where we started.