After mathematician Nela Sambashivan returns from her mother's bedside to England to teach, she finds everything has changed: there's been a shakeup in the department, her house and garden have gone to seed, and she can't get the American she met on the plane out of her mind. When she meets him again at a departmental party thrown by Ashoke, her childhood friend and present day colleague, the two embark on a brittle romance and scientific collaboration. As they draw closer, Ashoke's long standing jealousy flares up and he manages to betray Nela over a student's complaint. Nela's lover, Jackson, has left to finish an altruistic job in India, and Nela, seeing little left for her in her old life, decides to go to India to research collectives. She tells herself she is not looking for Jackson.
Nela finds shelter in a run down motel and is served by Ranu, a ten year old orphan. The two strike up a friendship as Nela takes the girl under her wing, teaching her, getting involved in her problems.
One day, when they are shopping in the market, Nela sees Jackson, delirious with fever and abandoned by his co-workers.With Ranu's help, Nela nurses him back to health and they re-kindle their love affair. They look after Ranu more and more, visit her village and help the elders. One of them, the treacherous Uncle, secretly arranges to marry Ranu off, but in a daring move, Nela and Jackson save her. Nela is wounded and takes refuge in Jackson's camp.
They know that uncle will exact his revenge, and they determine that Nela should take Ranu to England. Jackson will stay on, saving his corner of the world. The broken-hearted lovers cannot stay together, but marry to facilitate Ranu's entry into another country.
Once in Nela's old house, Ranu fails to adjust. Ashoke is up to his old tricks, too, and it is with great pleasure that Nela announces her marriage. She sees once again that there is nothing left for her in her old life, and she has made Ranu sacrifice everything known to her for a new beginning she does not like. She decides to take the child back to her old family home in India, looked after by an aged aunt, who welcomes them warmly.
In a bittersweet ending, Nela begins again, without Jackson, but with the knowledge that change is the only constant in life. As Chitti tells Nela in the closing scene, "anything is possible."