Arumpon is a village youth who loves his sister Thulasi. Arumpon holds a function for his sister despite hesitance from his maternal uncles, who disregard Thulasi for unknown reasons. Even his paternal uncles disregard Arumpon's family and consider Thulasi as a curse on their family. The only people who care for Arumpon's family are his grandfather Arunmozhivarman and his cousin Paramu. Arumpon likes his cousin Maangani, despite her father's disapproval. Arumpon actively looks for a match for his sister because his maternal uncle disapproves Thulasi to be married of to their sons. Despite Arumpon finding a prospective groom for his sister, his paternal uncle foils it, and Thulasi's engagement is called off. Arumpon and Paramu have a running feud with Ayyanar, a ruffian and his uncle, since they close Ayyanar's liquor shop and stopped them from selling agricultural land via a court order. So, Ayyanar decides to marry Thulasi for retribution. Arumpon reluctantly agrees to the marriage on his mother's and Thulasi's insistence. It is revealed that Thulasi is Arumpon's adopted sister who was the daughter of Dharma, a close friend of Arumpon's late father Chandrabose, who adopted Thulasi after Dharma's death.

Ayyanar tries to insult Arumpon at every turn, but Arumpon takes it with a light-heart since he is his brother-in-law. Thulasi was falsely arrested for Ayyanar's illegal liquor hoarding. When confronted by Thulasi, Ayyanar hits her. Arumpon mercilessly thrashes Ayyanar for retribution. Following this incident, Ayyanar's close friend Paari comes with men to seek him and go after Arumpon for retribution. In a heated exchange, Paari insults Ayyanar for getting beaten up by his brother-in-law and in a drunken stupor, Ayyanar kills Paari accidentally. After realising what has transpired, Paari's men attempt to kill Ayyanar. Ayyanar escapes from them but not with closely trailed by men out for blood. No one comes for Ayyanar's rescue but Arumpon, and Thulasi manages to rescue him and handover to the police. Enraged by this, they seek to kill Arumpon too. To end this problem without bloodshed, Arumpon, his mother, and his sister surrender to the panchayat. He explains that he knows the suffering of growing up without a father and wants to end this without further loss of life. Even though he can beat up every goon there and escape, he does not wish to do so. He offers to marry Paari's widow, but she compliments Arumpon's good nature and not wanting to make Thulasi widow agrees to end this peacefully.

During the film's closing credits, it is intended that Arumpon, Thulasi, and his mother have reconciled with the rest of the extended family. Ayyanar has been released on parole to attend Thulasi's Seemantham and it is revealed that he made peace with Arumpon. The film ends comically with Arumpon breaking the fourth wall mimicking his grandfather.