Police Constable Arumugam (Kaali Venkat) talks to the new Sub-Inspector, Arjun (Vijay Yesudas), about Maari (Dhanush), a local rowdy who rose to fame after killing a rival rowdy. Maari is an irritating guy, who, along with his henchmen Sanikilamai (Robo Shankar) and Adithangi (Kalloori Vinoth), constantly pesters the people in the area and extorts money from them. His main line of work is in training racing pigeons. His boss is Velu (Shanmugarajan), a bigger don who is also involved in the pigeon races, as well as the smuggling of sandalwood.

Maari constantly has fights with "Bird" Ravi (Mime Gopi), another local rowdy who is also working under Velu. One day, a lady named Sridevi (Kajal Aggarwal) enters the business, trying to open a boutique in Maari's area. Maari forcefully becomes her partner in the business, which angers her after she loses some customers. She decides to help Arjun catch Maari by getting close to him, pretending to fall in love with him, and incriminating him with evidence of his confession: he had tried to kill the rival rowdy, but failed. She shoots the talk with Maari in the drunken state, who describes about the murder, saying that somebody else had killed him, and he took the credit. Maari is soon arrested by Arjun. Seven months later, when he is released, he finds out that Velu also has been arrested, Arjun is actually a corrupt cop, and he and Ravi are working together and have arrested some people in the area under the pretext of smuggling, to extort money. Maari decides to take revenge on the duo. He first frees the local people from the extortion by Ravi's gang, while Sridevi also falls in love with him for real.

Later, Maari captures one of Arjun's smuggling vehicles and the driver, by which he forces Arjun to release Velu. When Arjun takes revenge by burning Maari's pigeon coop, which kills 10 of his pigeons, he gets angry and beats up Arjun, Ravi and their henchmen, where Ravi agrees to confess to everything. Angered, Arjun stabs Ravi but eventually gets arrested by the Revenue Department after Aarumugam reveals all of his secrets. Finally, Sridevi approaches Maari to confess her love to him, which he rejects, returning to pester the local people and extort them for cash.