The film begins with a train accident whose significance the audience will learn further on.
A young Bengali girl called Ashima (Tabu) trained in classical singing is arranged her marriage to a Bengali man called Ashoke Ganguli (Irrfan Khan) who has settled in New York. After moving to the US and leaving behind her family and the life that she knows, the two of them try to adjust to the way of life in New York and to assimilate the cultural differences. The food, the cold weather, a cramp flat in the middle of a big city where Ashima can't meet her neighbours, the language, everything is difficult for her. Ashoke is studying and working many hours, and that's difficult as well, for Ashima feels lonely many times. He is intellectual ambitions, and settles down better than her.
In time, the couple grow to love one another though it is hard to express their feelings, having been brought up to hide emotions between a man and woman. In time, Ashima gives birth to a baby boy, and the father who is studying for a PhD, names the boy Gogol in honor of the Russian author by the same name with whom he has a special affinity. But according to Bengali custom the child is given the "good name" of Nikil which is soon shortened to Nicky by his American acquaintances. In time another child is born, a girl named Sonia. Later, the audience will knwo the significance for Ashoke of that name.
Sonia (Shahira Nair as a teenager) will become a rebellious teenager herself. The cultural traditions of her culture doesn't offer her much place for fulfillment or professional ambitions. She feels like a fish out of water during their family reunions especially with her grandparents, (Ruma Guha Thakurta, Tanushree Shankar, Sabyasachi Chakraborty and Tamal Ray Chowdhury) who disregard her and ask her when she is going to settle down in marriage and have children. She doesn't have the need to do either, and the boyfriends she has will be met on her own terms. She moves down to California to lead an independent life.
Gogol (Kal Penn) grows up as a typical American teenager and, inspired by a family trip to the Taj Mahal in India, studies to become an architect. He finds love with Maxine Ratliff (Jacinda Barrett), an all-American blonde girl from a wealthy family. He feels soon a part of her family, which goes hand in hand with his distancing from his own family.
His father has to travel to Florida university for a week. During the travel, Ashoke feels a bit of a headache. Unexpectedly he dies from a heart attack. Gogol is forced to confront his fears about his cultural identity and rejects Maxine's attempts to support him through his intense grief, which ultimately ends the relationship. She tries to understand him, but he won't let her.
Gogol remembers the story his father told him: he came out alive of that train accident he shouldn't have. The person in front of him was Gosh (Jagannath Guha). Ashoke is reading a book by Russian classical author Nicholai Gogol and doesn't want to be bothered by Gosh, who points to the beautiful scener. Gosh dies, as should have done Ashoke, who is found by a rescue team.
Gogol meets an old childhood acquaintance, Moushumi Mazundar (Zuleikha Robinson), a second generation Bengali like himself, who has embraced the western way of life as keenly as he has. Their parents had hoped on their marriage, but neigher of them was interested. She had other secret plans, and he found her ugly, meek, and too obedient of her family's wishes. Now she 's becoming a business woman and has seen the world on her own. Without her glasses, with a modern hairstyle and western clothes, she looks sexy. She is good fun and ambitious.
They get married. Making love is very intense, especially for him. However, she likes to socialize much more than him, and he doesn't quite fit with her flamboyant intelligentsia-like boyfriends. The last drop is Moushumi's affair with a French ex-boyfriend of hers. Gogol finally learns to make peace with his culture and his circumstances. He and Moushumi acknowledge that no one is perfect.
Gogol wants to be alone in the USA for a while. All the oppposite, Ashima has decided to return to India and probably never come back to the USA. As usual, Gogol refuses his mother's help. She offers to call off a trip to India she's already bought the tickets for, but he tells her to go. He tells her that he's never felt free like this before.
