The film begins with the murder of a politician committed by the domestic terrorist Azhagam Perumal (Anandaraj). The corrupt home minister Ponnurangam (Goundamani) wants to become the state Chief Minister. He was one of the four founders of the ruling party, yet he has not become the CM, while his co-founders and junior have become the CM. Therefore, he orders Azhagam Perumal for money to create chaos in Tamil Nadu. Azhagam Perumal first sets off a bomb in the head office of the State's major opposition party. 22 people died during the bomb blast. Consequently, the incumbent Chief Minister (Raadhika) charges the new Anti Terrorist Squad's Assistant Commissioner, Suriya (R. Sarathkumar), to track down the terrorist group. Meanwhile, Suriya and Raji (Nagma) fall in love with each other.

Raji's brother Dinesh (Devan) is the one who has been tracking Azhagam Perumal for the last six months, before the blast. Though he is a close friend of Suriya, he is hurt when Suriya is given his case. Two of Azhagam Perumal's attempts to kill the CM goes in vain due to Suriya, and Suriya gets injured in the second attempt. Azhagam Perumal tells Ponnurangam to either remove Suriya from his path or find another guy to kill the CM. Ponnurangam, using his power as Home Minister and citing Suriya's injury, transfers him to the Anti-Prostitution Department. Dinesh is again given the responsibility of the case, and after misinterpreting a conversation between Suriya and the city commissioner, he gets angry with Suriya. Suriya then arrests Ezhilarasi (Vichithra), Ponnurangam's illegal concubine, who is the head of a huge brothel. Then, Suriya accidentally comes across Dinesh trying to capture a terrorist in the central station, and the police attempt goes awry. Dinesh begins to despise Suriya.

Then, Suriya is framed for going to a brothel when he was on an undercover attempt; therefore, he is suspended. An attempt is made on his life, which he escapes, but Dinesh is killed in his house, and Suriya's mother (Sangeeta) is also killed in a blast at his home. Suriya and Raji go and complain about Ponnurangam to the CM, but she is unable to do anything immediately as she is going on a state visit to Seychelles. Suriya accompanies her as her chief bodyguard. Meanwhile, Ponnurangam is watching the TV show of the CM's visit, waiting for her death, as he would immediately become the acting CM and then the CM. Raji comes there and holds Ponnurangam at gunpoint, but he snatches her gun and holds her at bay. An attempt is made on the CM's life, but Suriya still saves her and captures the disguised Azhagam Perumal. Ponnurangam commits suicide upon hearing that Azhagam Perumal was captured. All ends well.