The film opens with a flashback showing the family feud between families of Prabhakaran (Vijayakanth) and Bhavani (Indraja). Prabhakaran and Bhavani are in love. The murder of Bhavani's father, is wrongly accused on SP's father. He 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's his father who killed Bhavani's father. But 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 mom tells how his father had a different wife and he should ask them forgiveness. He storms into Bhavani's house and accuses her uncle (who really killed Bhavni's dad), also trying to make her understand the truth but she doesn't believe him. Then Prabhakaran says he doesn't love her any more and vows that he will never trust a woman by remaining a chronic bachelor forever.
Then 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. SP has a stepsister, Parvati (Swarnamalya), who is his father's daughter from the other wife. He now lives for her. But she doesn't know that SP is her brother, although she stays next door to him. Mayilu (Vadivelu) is SP's aide and he too is a bachelor. Gowri (Namitha) comes to stay in the hostel where Sandhya stays and tries to win the heart of SP. But SP considers her a nuisance.
SP agrees to take care of Kannan (Prabhu Deva). He is the son of Manivannan, his uncle who had helped SP to become a successful businessman. Prabhu Deva is a flirt and womanizer so his mother wants SP to take care of him and change his behaviours for the better. But what SP and his mother doesn't know is that Kannan has only agreed to stay in the house when he comes to know that Parvathi lives next door to SP and in order too woo her. Comical scenes recur throughout the movie, where Mayilu, who doesn't like Kannan and his friend Cheenu (Pandiya Rajan) staying with them, tries to get them out of the house. Gowri comes to know 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. But SP 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 it's wrong and walks away. At this time, Bhavani's brother and his gang come to kidnap her. While rescuing Parvathi from Bhavani's brother, Kannan decides to bring Gowri back too. Then Gowri's family members come to take her forcefully, but is 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's 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 whole-heartedly. He fixes the marriage of Kannan and Parvathi. He transfers everything he has to Parvathi's name because Kannan's family thought 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. But Parvathi tells that her mother loved him and told her to ask forgiveness if she sees him. Now Parvathi and SP re-unite as siblings. During the marriage festivities, Bhavani and her brother come to prevent the celebrations. Along with them comes the elder brother of Sandhya, 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 Parvathi lives happily and marries Kannan. Bhavani's household members uses Veerapandi to take advantage of SP; first by trying to snatch his company 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 who Parvathi will marry. She says she wants to be happy with both her brothers so to stop fighting. Parvathi has been emotionally forced to marry Bhavani's brother. She is rescued by Prabhu Deva, Mayilu and Cheenu. SP goes and pours kerosine on Bhavani to get her husband to tell the truth and he finally admits that it was him and his dad. He says how his father has done it for the money but he 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 only thing she can now offer is the marriage proposal of her sister Gowri to SP. SP initially refuses when Kannan tells that he'll also remain bachelor if SP doesn't marry. SP finally agrees and tells everyone to go inside with Gowri.