Anbuselvan is an honest, daring IPS officer with the Chennai City Police as the ACP in the Crime Branch. As he has no family or relatives, he lives with no fear. Anbuselvan and his IPS friends Srikanth, Arul, and Ilamaran are recruited for part of a special unit of police officers who are battling organised crime in Chennai. Violent and laconic, Anbuselvan finds little patience for his personal life. The unit is ruthless in its confrontation with criminals, going as far as assassinating gang members. The unit is finally disbanded after 5 encounters in 3 months, by Human rights authorities, where Anbuselvan is posted to Control Room Duties. One day, a school teacher named Maya rebuffs Anbuselvan's routine questions regarding safety, not knowing that he is a police officer.

Anbuselvan meets Maya again when she and her friend are questioned for driving without a license. However, Anbuselvan lets them off with a warning. When one of Maya's students has a problem with local kids, she asks Anbuselvan for help. Anbuselvan resolves this problem, a mutual respect grows between them, and they begin seeing one another. When Maya gets into a road accident, Anbuselvan helps her recover, and they fall in love. Srikanth and his wife Swathi become good friends with Maya. Sethu is a gangster, who escaped the encounter operations, meets his estranged brother Pandiya, who returns to Chennai after 14 years of crime life in Maharashtra. Pandiya has a peculiar tactic: he kills a family member of his opponent, but leaves the opponent alive to rot in failure and depression on the loss of his family member.

Sethu's gang, aided by Pandiya's planning, commit major kidnappings in the city and become very powerful in 6 months. The 10-year-old son of an influential movie producer is kidnapped and killed, and later his daughter is also kidnapped for ransom. The special unit is reassembled by the commissioner with all four back in the crime branch. The unit tracks down and kills Sethu in a railyard, as others escape. Pandiya takes over the gang, promising grave revenge over his brother's death. Pandiya and his gang members target the families of the men in the special unit, but the police close in, and a badly injured Pandiya barely escapes Anbuselvan. Pandiya and his men brutally kill Ilamaran the same night, and escape. The entire department is mobilised, and all family members of the remaining three are sent into hiding. Maya and Anbuselvan get married in a hurry and leave for Pondicherry.

However, Pandiya and his thugs enter the cottage the next day where the couple are honeymooning and attack Anbuselvan, leaving him for dead, and kidnapping Maya. Anbuselvan is battling for life but thinking only about rescuing Maya. Srikanth and Arul arrive at the cottage, discover Anbuselvan, and take him to the Pondicherry Government Hospital. Srikanth reveals that Swathi was kidnapped earlier at the airport and confesses that it was he who gave away Anbuselvan's location to Pandiya, for Swathi's safe return. Srikanth feels extreme remorse over what has happened. Whilst in the hospital, they receive a message from Pandiya to meet him at a particular location in Andhra Pradesh. When they go there, they find two packages, one containing Swathi's severed head and the other one containing Maya's arm flesh.

Srikanth and Anbuselvan are distraught, with the former being hysterical upon seeing his wife's head, and in an agony of grief and guilt at being responsible, he shoots himself dead. Anbuselvan and Arul track down Pandiya before he can escape from Tamil Nadu and fight with the gang. Anbuselvan aims to shoot Pandiya, but Pandiya ends up shooting Maya while using her as a shield, and she dies in Anbuselvan's arms. An enraged Anbuselvan tracks down Pandiya and brutally finishes him off, avenging Maya and his friends' deaths. An epilogue shows that Anbuselvan, after the death of Maya, continues his job as an IPS officer some months later, while still reminiscing his moments with Maya.