Nagin iwhere according to a myth, when snakes are of certain age, they can assume human form. Thus, the film begins with a male and a female in their human forms, singing and dancing amorously with each other. When the male turns back into a snake, he is shot by a member of a hunting party, who thought the snake was going to attack the woman. The rest of the story deals with the female taking revenge on the group of friends responsible for her lover's death. In the end, Vijay is the only one alive and the nagin dies before killing him and realizes that she was wrong and that her revenge destroyed many lives just like her own life was destroyed. Near death, she sees her beloved in the sky calling out to her. She dies and reunites with him in heaven.