Naachiyaar (Jyothika) is a tough policewoman in Chennai who is put in charge of solving an underage rape case. She tracks down a pregnant Arasi (Ivana), the victim, from her uncle and his goons who plan to get her an abortion. Although Naachiyaar saves Arasi, her uncle and his friends escape and go into hiding. Meanwhile, Naachiyaar’s partner, Feroz arrests the suspect, Kaathu (G.V. Prakash Kumar). He is then sent to a juvenile home, where he tells his story to one of the wardens, who is soft-hearted towards him.
Through flashbacks, we see how Kaathu and Arasi first met. Both are still teenagers from the slums but they do not go to school but are forced to work to help support their respective families. Arasi works as a maid at wealthy families’ homes while Kaathu does odd jobs for a living. One day, while her employers are away, Arasi invites Kaathu into the house where they (impulsively) make love. However, Arasi quickly regrets and pushes Kaathu away, who leaves upset.