Kathiresan is an honest and rightful cop. His passion for his work and honesty leads to him being brutal to the culprits. His way of inquiry is way too harsh. This causes his colleagues and higher officials to show faces to him. Kathir is from a middle-class family. His father is an ex-military official. His elder brother Viswa is an army man. He lives with his sister-in-law, father, and niece Shruthi. Kathir has a girlfriend named Darshini, who is his sister-in-law's cousin.

Here comes Prabhakaran, who is a spoiled youth. He hails from Madurai and lives with his friends. In order to earn money, they kidnap young kids and demand a ransom from their parents. Once, they kidnap the son of a rich man named Mahendran. Mahendran personally knows the commissioner, and the case goes to the police. Together, with the rich kid, they kidnap a poor man's child, as well. A ransom of five crores is demanded. The ACP delays it, which causes the poor kid to die. Fearing his own son's life, Mahendran gives five crores. Then, Prabha asks Kathir to give the money to some lady on the train. As that, Kathir sees a lady with her son and gives her the money. He gets onto the next compartment. The guy slaps the lady and escapes with the money. Kathir is led to a room in a flat and kills the guy, Kutty. He saves the money and the kid. The department suspends Kathir, as he was told not to shoot the culprit.

The kidnappers, angered by the death of their friend, vow revenge. They hit Sruthi while she comes back from school. The whole family goes to the hospital, and the guys come there. They were unable to kill the rest as Kathir is present. One of them later calls Kathir and threatens him. His father tells him to kill all of them in a day's time. The clock starts ticking at 9 PM. Kathir later finds the guy and kills him afterwards. Another man named Sekar enters and flees after seeing Kathir and his friends, Arun and Parthiban. He informs Prabha and is soon killed by them. When they go to Prabha's residence, they find nothing. Prabha still tries to kill everyone, including his sister-in-law's parents, but Kathir saves them. Later, when he brings them to the police station for safety, he sees the small boy from the train. He realizes that he is a pickpocket and that the lady is not his mother. He finds her name as Kasturi and brings the boy along to find her. Her flat is also empty.

Kathir's father is killed at his house by Prabha. Kathir hides this from his family and asks them to stay at the hospital. Meanwhile, two men enter the hospital but find the police and Viswa there. Arun is later killed on the road. Later, Parthiban's son is kidnapped. They track that this is Prabha's gang. When talking with Prabha, they realize that their car is stalled at a police checking. Despite the information, the police loses them. A chase ensues, but they discover that the boy is not in their car.

Kasturi has the boy and hides in a beach house. Prabha and his other friend Guna are there. Kathir tells the pickpocket boy to keep watch. Later, he and Guna get caught. Viswa is lured into the car park and gets stabbed but survives. Kathir later escapes with the pickpocket boy's help. His sister-in-law is later asked to go buy medicines by the disguised Kasturi. When Sister-in-law is outside, Prabha comes to stab her but is unsuccessful. Kathir chases them and kills them all, including Kasturi.