True to it's title - which means three knots - the story revolves around three characters and the unexpected happenings in their lives. Balaji (Kamal Haasan) and Prasad (Rajnikanth) both fall in love with a young, college girl Selvi (Sridevi) who lives with her sister Subhadra. Balaji and his roommate Prasad are bachelors who live alone in the same neighborhood Selvi falls in love with Balaji and does not reciprocate Prasad's feelings. Prasad is unable to face the rejection by Selvi. So, he gets Balaji out of his way. Selvi is furious but helpless. Her misfortune continues as she loses her sister also. She is left with no option but give her consent to marry Prasad. Will she now accept Prasad's love or does she seek revenge for her lover's death? Selvi chooses a novel and interesting path which forms the rest of the story.