IG Ranjith (Prakash Raj) recalls the memories of a criminal whom he failed to capture.

Annachchi (Kota Srinivasa Rao) rules a village in western Tamil Nadu. When he is opposed by Mambattiyan's (Prashanth) father Chinnasamy (Vijayakumar), the "jameen" kills him. Coming to know of this, Mambattiyan kills Annachi and those in support of him. A group of youngsters in the village join hands with Mambattiyan. They lead a life in a forest. By robbing the rich and distributing the wealth to the poor, Mambattiyan becomes the local Robin Hood.

Meanwhile, police forces led by Ranjith go from pillar to post to nab Mambattiyan. This is the start of a cat-and-mouse game between the two. Also, Mambattiyan has romance in the form of Kannathal (Meera Jasmine) and Sornam (Mumaith Khan). When Sornam raises a green flag, that means she needs him to come. An officer in disguises realizes this and reports it to Ranjith, so one by one, all of his gang members die. Sornam later commits suicide.

Meanwhile, Kannathal panicked and asked Mambattiyan to go to a faraway place and forgo his Robin Hood job. Mambattiyan agrees and asks her to wait at the river. With the help of Bullet (Ravi Shanth), a villager, Kannathal waits at the river. Mambattiyan defeats the police forces and escapes. However, Bullet shoots Mambattiyan because whoever captures Mambattiyan gets a rewards of money and land. Kannathal hits Bullet, and he dies, then she dies too.

At the end, Ranjith is sad that the whole village is crying, and he takes Mambattiyan's chain.