The film opens with a flashback showing the family feud between the families of Sundaralingam Prabhakaran and Bhavani Easwaramurthy. Prabhakaran and Bhavani are in love. The murder of Bhavani's father Easwaramurthy is wrongly accused on SP's father Sundaralingam. Prabhakaran starts to help Bhavani's family and mortgages his own house to finance her factory with the intention of making it up to them as he still believes that it is his father who killed Bhavani's father. However, Bhavani is now trying to take revenge for her father's murder. SP's mother is now on her deathbed. While in the hospital, his mother tells how his father had a different wife and he should ask them forgiveness. Prabhakaran storms into Bhavani's house and accuses her uncle (who really killed Bhavani's father), also trying to make her understand the truth, but she does not believe him. Then, Prabhakaran says that he does not love her anymore and vows that he will never trust a woman by remaining a chronic bachelor forever.

Then the film comes to the present time, showing a legal battle between Prabhakaran (now called SP) and Bhavani. Bhavani becomes furious when SP wins the legal battle to get back his house. She threatens to destroy SP. From here, the story moves to the day-to-day life of SP and falls into a comic track throughout the first half. SP is now a successful businessman. He has a stepsister named Parvathi, who is his father's daughter from his other wife. He now lives for her, but she does not know that SP is her brother, although she stays next door to him. Mayilsamy is SP's aide, and he too is a bachelor. Gowri comes to stay in the hostel where Parvathi stays and tries to win SP's heart, but SP considers her a nuisance.

SP agrees to take care of Kannan. Kannan is the son of Manivannan, his uncle who had helped SP become a successful businessman. Kannan is a flirt and womanizer, so his mother wants SP to take care of him and change his behaviors for the better. However, what SP and his mother do not know is that Kannan has only agreed to stay in the house when he learns that Parvathi lives next door to SP in order to woo her. Comical scenes recur throughout the movie, where Mayil, who does not like Kannan and his friend Cheenu staying with them, tries to get them out of the house.

Gowri learns that SP is sponsoring Parvathi's studies and confronts him. SP tells her that Parvathi is his sister. Gowri then asks Parvathi to call SP for her birthday party. SP then gets upset and confronts Gowri. Gowri then reveals that her sponsor was SP all the while. During the birthday party, Bhavani comes and takes Gowri away. Then, it becomes clear that Gowri is Bhavani's sister. Rivalry arises between Gowri and Bhavani. Parvathi starts showing affection towards Kannan but says that it is wrong and walks away. At this time, Bhavani's husband Durairaj and his gang come to kidnap her. While rescuing Parvathi from Durairaj, Kannan decides to bring Gowri back too. Then, Gowri's family members come to take her forcefully, but they are stopped by Kannan. When told off by SP for doing so, he tells Mayil that he will sponsor the girl that loves SP like how SP sponsors the girl that he loves.

That is when SP asks Parvathi to move to his house. Kannan and Cheenu are moved to the guest house. Parvathi shows affection to Kannan. One day, SP and Mayilu catch Kannan trying to reach Parvathi through the balcony. That is where SP knows that both of them love each other. He tells Kannan to promise that he will never look at another girl in his life, and she (being Parvathi) should be the only one, which Kannan agrees to wholeheartedly. He fixes the marriage of Kannan and Parvathi. He transfers everything that he has to Parvathi's name because Kannan's family thought that Parvathi was an orphan. SP tells everything to Kannan's parents, which is overheard by Parvathi, who runs home crying. SP upset runs to comfort her, where he explains how he will live his life as an apology to her mother's curses. However, Parvathi tells that her mother loved him and told her to ask forgiveness if she sees him. Now, Parvathi and SP reunite as siblings. During the marriage festivities, Bhavani and Durairaj come to prevent the celebrations. Along with them comes the elder brother of Parvathi, Veerapandi. He challenges SP, saying that he has more right over Parvathi as he is her brother, while SP is just a stepbrother. Veerapandi then claims all of SP's property, which SP is willing to give, provided that Parvathi lives happily and marries Kannan. Bhavani's household members use Veerapandi to take advantage of SP; first by trying to snatch his company and then trying to snatch his home. In the brawl, SP vows that Parvathi will marry Kannan and he will wipe off everyone who stands in the way. Bhavani then tells SP that Parvathi will be married off to Bhavani's brother. Veerapandi supports in the name of revenge.

Parvathi, torn between two brothers, comes running when the brothers fight among themselves on the account of whom Parvathi will marry. She says that she wants to be happy with both her brothers so to stop fighting. Parvathi has been emotionally forced to marry Durairaj. She is rescued by Kannan, Mayil, and Cheenu. SP goes and pours kerosene on Bhavani to get her husband to tell the truth, and he finally admits that it was him and his father. He says how his father has done it for the money but he had done it because he loved her and she was his life. Bhavani realizes her mistakes and goes to SP's house to apologize, but she tells SP that the only thing that she can now offer is the marriage proposal of her sister Gowri to SP. SP initially refuses when Kannan tells that he will also remain bachelor if SP does not marry. SP finally agrees and tells everyone to go inside with Gowri.