Siva (Dhanush) is a happy-go-lucky young boy in a large family. The head of this family are three brothers: Raghupathi (K. Bhagyaraj), Raghavan (Vijay Babu), and Rajaram (Vivekvasu Nagalla). One of the brothers is Siva's father. Siva studies from a hostel away from home. He is always helpful and always comes in when others need him. In one of his obliging acts, he helps his cousin Kalpana (Shriya Saran) elope with her lover against the family's choice. This aggravates the family, and they are asked to forget all about him.

On another occasion, he is asked to help a friend in a love marriage. Siva kidnaps Pooja (Genelia) on a mistaken identity from the marriage hall. When Pooja is kidnapped, her uncles Periyamuthu Gounder (Ashish Vidyarthi) and Chinnamuthu Gounder (Jaya Prakash Reddy) and their henchmen follow them. Pooja, while on the run, tells Siva that she was not interested in the wedding and that her uncles are forcing her marriage with one of their sons, only to seize her properties. When Siva went to kidnap her, she was thinking of how to run away from this marriage. While escaping from Pooja's uncles, Siva brings Pooja to his house under a false identity. Soon, Siva falls in love with Pooja and determines to marry her only with the consent of all the members of both families. When Siva's family along with Pooja visit a temple, her uncle kidnaps her and locks her away in his house.

To save Pooja, Siva joins Emotional Ekambaram (Vivek) – the auditor of Pooja's uncles – as an assistant. He makes Ekambaram believe that he is capable of creating new worlds with characters of their own. Ekambaram then "creates" two American billionaires and with the help of Siva, convinces the two uncles to marry their sons to the daughters of these billionaires. To prove that they are real and not merely the figment of Ekambaram's imagination, Siva asks his parents and his uncles and aunts to play the role. They manage to win the Gounders' hearts and bring about a change in their behavior.

Then, with the consent of all the family members, Siva marries Pooja.