An encounter specialist learns the hard truth that all his encounter operations have been to safeguard the interests of corrupt politicians and businessmen. But before he can undo the damage, it is too late; and four innocents become collateral damage as well.

Kathirvel Murugan (Bharath) is a software engineer in Chennai. He shares his room with friend Sakkarai (Santhanam). Kathir hails from Usilampatti but wants to project him as city-bred and his ambition is to settle in USA. Kathir's father Sevaka Pandian (Sampathraj) is against his son's attitude. An influential local chieftain, he is against inter-caste marriage and love. Kathir meets Nisha (Rima Kaleengal), who too wants to go abroad. The latter loses her passport and Kathir helps her find it. Slowly Kathir falls for her. Meanwhile, Sevaka Pandian arranges for his son's wedding with a High Court judge's daughter. In the meantime, Kathir and Nisha get their visa and get ready to leave together for USA. The former thinks that he has escaped from his marriage and when he wants to propose to Nisha, he gets a rude shock. She informs him that she is going to USA for her marriage. What happens after this forms the rest of the plot.

Shiva gets nostalgic thinking about his college life and friends and looks forward to meeting them all. But, there is a sombre mood at the reunion. Soon, Shiva is found almost strangled to death.