Karthik and Shakthi in their apartment Karthik desperately phones for Shakti Karthik (Madhavan) is an engineering graduate who happens to lay eyes on Shakti (Shalini), a medical student, at a wedding. The two meet regularly after their initial sighting, on suburban trains, to and from work and university. Karthik and Shakti eventually fall in love. Karthik's father Varadarajan, a lawyer, comes to learn of the two's relationship and approaches Shakti's dad Selvaraj. He asks Selvaraj, a railways employee, for his consent to a marriage proposal between the two young lovers. However, upon meeting, the two parents clash, and the wedding is called off. Shakti decides she will not get married without her parents' consent, and the relationship between herself and Karthik is called off altogether. Unable to stay separated for very long, coupled with chance meetings, Karthik and Shakti find themselves resuming their relationship, albeit secretly, without the knowledge of their respective families. They decide to get married, without telling anyone, but carry on living with their parents, hoping that a time will come when both families will see eye to eye and can be told of the development. With the help of their friends, and Shakti's elder sister Poorni, their marriage is completed legally, and all the while, they continue to meet each other without their parents' knowledge. Shakti's elder sister Poorni is approached with an engagement proposal soon after. Poorni is willing to accept the offer to marry the suitor - Raghu. The prospective groom's father offers his second son's hand in marriage to Shakti. Shakti's mother Saroja urges her to accept the marriage proposal, unaware of the fact that Karthik and Shakti are already together. Shakti eventually tells the truth, and Poorni's engagement is called off. Karthik and Shakthi are kicked out of their homes. With the help of friends, Shakti and Karthik move into an apartment, in development. They cope for a while, however it's not too long before the couple start arguing over various issues that the two seemed so much more tolerant of before they got married. Marriage tension escalates. Shakti comes to learn that her father is seriously ill back home. She and Karthik decide it would be best to visit him. Upon arrival they learn that her father has passed away. Wracked with guilt, the two return home, their relationship taking a turn for the worse. The two stop talking to each other. Meanwhile, Karthik takes it upon himself to sort out Poorni's adjourned marriage proposal to Raghu. He arranges a blind date between the two, which initially fails, backfiring on Karthik, however, with more meetings, Poorni and Raghu become closer. This development takes place without Shakti knowing. She and her husband have not spoken to each other for a long time. Karthik wishes to wait until Poorni and Raghu's marriage is confirmed before telling Shakti. Poorni is desperate to tell her sister the news herself. Whilst hugging Karthik, thanking him for his efforts, Shakti witnesses their close contact and mistakes it for something else, leading to an even bigger argument, and a trade of insults. Shakti eventually learns of her husband's efforts in getting her sister married, and wants to thank him. Karthik sets off to the railway station to collect his wife, she has left the hospital where she works, but isn't on the train she usually takes. Karthik sits down on a nearby bench and waits for his wife. Meanwhile, in a bid to rush home, Shakti meets with a car accident, which leaves her fighting for her life. She is hit by a car driven by a lady (Kushboo in a special appearance). The woman's husband (special appearance by Arvind Swamy) ensures that Karthik is informed about the accident. Finally Karthik meets his wife in the hospital,where she is fighting for life. In these turn of events Karthik understands the true meaning of love. Movie ends with Shakti opening her eyes coming out from coma.