The movie starts with Thirunavukkarasu(alias Arasu) murdering a person in Mumbai. Soon, the story shifts to Kumbakonam where Arasu is employed in a temple by Venu Shastri, and stays in Pichumani's house. Arasu's calm nature and responsible behaviour impresses everyone in the locality. Meera, Venu Shastri's daughter, falls in love with Arasu. One day, Arasu sees the news about the release of a criminal from jail and gets angered. He also kills the criminal with the help of a few men. The murder is witnessed by Meera and Venu Shastri.

Everyone in Kumbakonam gets shocked upon knowing that Arasu is a murderer. Arasu meets Venu Shastri's family to disclose the truth. A flashback is shown where Arasu is the only son of Nataraj, who is fondly called Periyavar by his followers in Chennai. Periyavar is a good-natured don striving hard for the welfare of the poor and slum dwellers in Chennai. He is married to Sivagami and they lead a happy life with Arasu.

Sabapathy is a rich business tycoon who goes to any extent for earning money. Trouble erupts between Sabapathy and Periyavar, following which Sabapathy is arrested and sentenced to imprisonment for his illegal activities which led to the deaths of a few young girls. As a means of revenge, Sabapathy's brother Gunashekharan and his henchmen kill Periyavar and Sivagami. Arasu is angered and vows revenge against Sabapathy and his men. Hearing this, Venu Shastri and Meera understand Arasu's position and decide to save him by not disclosing his whereabouts to policemen.

Despite all the attempts by police to arrest Arasu, he successfully kills Sabapathy and Gunashekharan and surrenders to the police. He is sentenced to imprisonment and gets released after five years. In the end, he comes to meet Meera, and both get united.