Vaibhavari Sahay affectionately called Badki (Rani Mukerji) and Shubhavari Sahay, affectionately called Chutki (Konkona Sen Sharma) are the daughters of Shivshankar Sahay (Anupam Kher) and Sabitri (Jaya Bachchan). They live together on the banks of the Ganga (Ganges River) in Banaras. Life is full of happiness and joy for the two, though the family is relatively poor. Badki especially is protective of her family and is determined to ensure Chutki completes her education.

As things go from bad to worse, Badki goes to Mumbai to find work. After encountering many obstacles and feeling desperate and out of options, she is forced to become the exclusive call girl "Natasha". Misleading her family, by telling them she is an event planner and sending them money for her father's medicines and to keep the family home from being foreclosed on, Badki hides her secret. Chutki completes her MBA and, unannounced, comes to live with Badki in Mumbai. The younger sister becomes a trainee at the agency Matrix Advertising, and Chutki falls in love with her boss, creative director Vivaan (Kunal Kapoor). Badki finds love in attorney Rohan (Abhishek Bachchan), but leaves him, afraid that he would be disgusted by her profession. Chukti inadvertently discovers what Badki does for a living.

The two sisters return to Banaras for Chutki's wedding; Badki also comes face to face with Rohan, as he is revealed to be Vivaan's brother. Old feelings resurface between the two and eventually Rohan asks Badki to marry him. Badki refuses, feeling that Rohan would never accept her after knowing her profession. Chutki convinces Badki to think about her happiness for once and accept his proposal. During the conversation Shivshankar, Sabitri and Chutki finally face the lies and secrets realising what Badki sacrificed for the family. Badki reveals her profession to Rohan who shocks her by announcing that he knew from the moment he saw her with her client in Zurich, that she was a call girl. Despite that he still wants to marry her in which Badki readily accepts finally gaining the happiness she has sought for.