Shanmugam (Sarathkumar) is the village head, fondly called Nattamai in his village in Coimbatore. He sits on the ancestral throne in his village to do justice. He hears all the cases and gives solutions to the people and punishments to the wrongdoers. His wife Lakshmi (Khushbu) admires and respects him. His brothers Pasupathi (Sarathkumar) and Selvaraj (Raja Ravindra) fear him but also have a lot of respect for him as he has brought them up as his children. Pasupathi marries Meena (Meena), the daughter of an industrialist (Vinu Chakravarthy). She dislikes Shanmugam Nattamai because of his verdicts and attitude and her husband for being so timid with his brother but later transforms after learning of the former's greatness from her father. Selvaraj loves his paternal cousin, who is his paternal aunt (Manorama) granddaughter Kanmani (Sanghavi).

In the flashback, Periya Nattamai (Vijayakumar), Shanmugam Nattamai's, Pasupathi, and Selvaraj's father, orders Manorama's son (and Kanmani's father) (Ponnambalam) to marry his servant's daughter whom he raped. Manorama (who is Periya Nattamai's brother) begs him to forgive her son, however, he asks her to not interfere with his judgments. His brother-in-law, (Ponnambalam's father and Manorama husband (Erode Soundar), shoots him as he is disappointed by his verdict. Enraged, Periya Nattamai gives his final judgment before dying. He expellees Ponnambalam's family from the village and makes Shanmugam the new Nattamai, before dying.

Years later, Ponnambalam's father dies. Ponnambalam builds envy on his uncle's family and waits for an opportunity to take revenge on them. He hires a woman as the village school teacher and asks her to make Pasupathi fall for her. She does so to save her father, who is in the hands of Ponnambalam. He kills her and makes the villagers believe that Pasupathi has committed the murder. Shanmugam Nattamai sentences ten years of exile for Pasupathi, and his wife Meena. Ponnambalam learns of his daughter's love for Selvaraj and tries to kill him, with the help of his goons. Pasupathi goes to his rescue of him, and a pregnant Meena goes to Shanmugam to convey this message. While Pasupathi starts to take revenge on Ponnambalam, Manorama rushes to Shanmugam, kills her son Ponnambalam, and reveals the truth and tells that he punished his brother without committing any mistake and also told that the crimes blamed on Pasupathi were really perpetrated by Ponnambalam. Shanmugam dies upon learning that he gave a wrong judgment, and Pasupathi is shown taking his place as the new Nattamai.