Vasudevan (Dhanush) is from a middle-class family. He makes several bids to obtain employment, but all goes in vain due to his poor language skills and inadequate education qualifications. All his friends settle in life, but he continues to struggle in finding work. Vasu has two faithful friends in Cheenu (Karthik Kumar) and Ganesh (Karunaas). His father (Raghuvaran), who is a teacher, is always critical of him for being an irresponsible person. This adds to his woes.
At this juncture, Vasu glimpses a woman named Keerthi (Nayanthara) and immediately falls in love with her. He learns that she works for a software solutions firm. Luckily for him, Vasu secures employment in the same firm. Keerthi eventually turns out to be a short-tempered young woman. On a business trip, Vasu accompanies her with two other colleagues (Jeeva and Manobala), to Australia. Here he reveals his feelings of love to her. She immediately turns him down, saying that she comes from an Orthodox family, and her marriage has already been arranged with her uncle's son.
A depressed Vasu returns to India thereafter. Unable to see his son in depression, his father decides to meet Keerthi. She abuses him for recommending his son's love and accidentally slaps Vasu and his father. Later that night, Vasu's father dies of heart attack. To help change Vasu's mood, Cheenu persuades him to come to his family house in the country. Coincidentally, on the train journey, Keerthi is revealed to be Cheenu's fiance. However, their grandfather's (K. Viswanath) thoughts of getting them married earlier are put aside because Cheenu and Keerthi leave the house to have their own identity. This causes heartburn to their grandfather.
With the passing of a few days, Keerthi and Cheenu's parents decide to get them married to appease their grandfather. After several turns of events, Keerthi realizes that she is in love with Vasu instead. Vasu asks her to forget him because he believes that it would create problems in their happy family. Cheenu overhears their midnight conversation. During the wedding, Cheenu tries to force Vasu and Keerthi to confess their relationship to everyone. But when they hesitate to do so, Cheenu stops the marriage himself, by lying to his elders that he has a secret wife in Chennai. When Cheenu comes under fire from his relatives, Vasu tells them the truth and is driven out of the house. He is joined only by the grandma of the house, who agrees to accompany him as she reminds Vasu of his late father.
In time, the rest of Cheenu and Keerthi's family comes to stay with him for a few days. But Cheenu's grandfather refuses to enter the house, telling Vasu he is still angry with him and needs time to change himself somehow. The movie ends when Vasu and Keerthi become a happy couple and live together happily.