Bhoominathan (Vijay) idolises Muthuramalingam (Rajkiran) and at the request of his parents, accepts to work for the latter as his bodyguard. There enters Muthuramalingam's rival, who has lost his daughter since she committed suicide, the reason being rejection by Muthuramalingam's son. While Bhoominathan protects Muthuramalingam, his rival threatens the life of his daughter Meera (Asin).
Bhoominathan is sent to college along with Meera and her friend Madhu (Mithra Kurian) to protect them from the threat. Meera tries to distance herself from Bhoominathan by calling him from a private number; Bhoominathan falls in love with the girl without knowing that it is Meera herself.
At one point, Meera too feels herself becoming attracted to Bhoominathan and expresses her desire to meet him in person. However due to circumstances they are not able to accomplish this until at the climax when she tells Bhoominathan to run away with her and to meet at a railway station. Bhoominathan agrees, unaware it is Meera.
However through certain means,Muthuramalingam comes to think that Bhoominathan and Meera are going to run away. In order to save Bhoominathan's life from the anger of Muthuramalingam, Meera lies that the lover is not her and that Bhoominathan is meeting another girl at the train station. Muthuramalingam lets Bhoominathan leave as he is desperate, but tells his henchmen to kill Bhoominathan if a girl does not come there at the station (which implies that Meera loves Bhoomi).
Terrified, Meera sends her friend, Madhu, to the station and tells her to tell Bhoominathan that she is the lover and that she won't be able to make it to the station. Madhu, seeing Bhoominathan, falls in love after all that has happened, and pretends that she is the lover. Meera calls her, but Madhu throws the cellphone away, hoping to erase Meera out of their love life completely. Many years later, after Bhoominathan and Madhu's marriage, they have a son.
Madhu passes away shortly after however before her death, she leaves a diary for her son that outlines the whole story between the phone calls of Bhoomi and Meera and their love. The son later goes to Meera's house with Bhoominathan to visit an old Muthuramalingam. Bhoominathan is shocked that Meera isn't married. The son asks Meera to come with him and become his mother and Bhoominathan is angry at his son for saying something so blunt and rude. But Muthuramalingam begs Bhoominathan to take Meera as his wife. So they go onto the train together but the son runs away before leaving and throws the diary into a trashcan nearby.
Bhoominathan finds the diary and realises soon that his real lover, the girl who had waited for him for so many years faithfully, was Meera. And in the train he shows that he has accepted her full-heartedly.