Shanmugam is the grandson of the rich landlord Kulasekaran based at the Karamadai area in the Coimbatore District of Tamil Nadu. Upon his parents' early death, Kulasekaran transfers all his wealth to Shanmugam and passes away. Shanmugam is raised by his paternal aunt Lakshmi. However, Lakshmi's husband Rajarathinam is greedy about money and tries to kill Shanmugam. To save Shanmugam from her cruel husband, Lakshmi lies with the help of their family lawyer Naachiyappan that the entire wealth is transferred to her name and let Shanmugam grow as a servant in the same home.

Shanmugam is very fond of Lakshmi and treats her as his own mother. Shanmugam falls in love with Shakuntala who is employed in the same house. Kannamma is the only daughter of Lakshmi and she returns to the village post completion of her studies from abroad. While Lakshmi dreams of marrying Kannamma to Shanmugam, she has other plans. Kannamma discloses that she is in love with her classmate Raja. Although not interested, Lakshmi agrees for the wedding. One day, Shanmugam is sick and Sakunthala plays a prank on him without knowing by making him jump in the river which makes his condition worse. However, Shakuntala saves him, but Shanmugam shivers in cold. Accidentally, they both enter into a physical relationship and Shanmugam promises to marry her. Meanwhile, on the day of Kannamma's marriage, Raja and his parents cancel the wedding knowing that all their properties actually belong to Shanmugam only. Rajarathinam gets shocked knowing the truth. To save the life of Kannamma, Lakshmi requests Shanmugam to marry her. As Shanmugam could not turn down her request, he agrees and marries Kannamma.

To Shanmugam's shock, Shakuntala gets pregnant so she decides to leave the village as she does not want to interrupt Shanmugam's life once again. But Shanmugam stops her and accommodates her in their farmhouse, which is managed by Mani, Rajarathinam's sidekick who was a corrupt person but has just reformed after seeing their sacrifices for each other and feels proud of them. Shanmugam secretly visits Shakuntala and takes her to hospital for periodical check-up. Kannamma also visits the same doctor once and she spots Shanmugam and Shakuntala together. Kannamma feels heartbroken but understands the situation of Shanmugam. Shakuntala discloses the truth and speaks in favour of Shanmugam. Rajarathinam's henchmen try to kill Shakuntala and her baby. But she is saved by Kannamma and the baby is delivered successfully. Shanmugam, with a greater upper hand, fights with and defeats both his own uncle and his henchmen. Finally, Shanmugam is married to Shakuntala but begins a fresh life with Kannamma, on Shakuntala's advice and hence the movie ends with a happy ending.