Themes of cultural and generational difference merge and clash in Mira Nair’s sprawling but affecting family drama, marked by sensitive direction and fine performances. “The Namesake,” based on a novel by Jhumpa Lahiri, shows its literary roots in its rambling, episodic nature, but despite the fact that it sometimes feels cumbersome and overstuffed, it carries a substantial emotional impact.

The film runs along two basic, interrelated tracks. One involves Indian couple Ashima (Tabu) and Ashoke (Irrfan Khan), wed in an arranged match in the late 1970s after he’s miraculously survived a terrible train wreck. Following the ceremony they move to America, where they soon have their first child, a boy whom they name Gogol after the Russian writer whose book Ashoke had been reading just before the accident. The second major thread centers on Gogol (Kal Penn), shortly introduced as a rangy, rebellious (and thoroughly Americanized) high school senior. He goes off to college and becomes an architect who calls himself Nick and gets engaged to Maxine (Jacinda Barrett), the beautiful blonde daughter of a WASPy high-society East Coast couple. But a family tragedy intervenes that unravels his plans and leads to his marriage instead to an Indian girl named Moushumi (Zuleikha Robinson)—a union that has difficulties of its own.

This precis, while accurate enough, doesn’t really do justice to the richness and texture of the film, which naturally derives from the astute writing and direction, but mostly from the extraordinary performances of the three leads. Tabu and Khan both manage to create vivid characters while maintaining outward restraint; they also age convincingly over the course of the narrative—no small feat, due here only in small measure to the excellent makeup. But the real revelation is Penn, whose work has previously been limited to comic parts. As Gogol he shows substantial dramatic range, moving from a sullen, smart-aleck teen to a mature man coming to terms with his background very convincingly. The subordinate characters aren’t nearly as well drawn, but Jacinda Barrett and Zuleikha Robinson, as Gogol’s fiancJe and wife, both register reasonably well.

From the technical perspective “The Namesake” isn’t as slick as one might expect—Frederick Elmes’ cinematography actually captures a bit of the untidiness of the story in visual terms. But it uses the varied locations—both exterior and interior—well, and Nitin Sawhney’s score complements the changes nicely.

The result is a family drama that will appeal with special force to those who share the Bengali heritage of the principals. But the themes and problems it raises are universal, and the film should be embraced warmly, warts and all, by a much broader audience than that. It’s a solid and affecting piece of work.