The film begins with Guru Moorthi (Prakash Raj) who follows Pooja (Easwari Rao) like a mental. Guru Moorthi claims to be Mahendra Boopathi in his past life and he was in love with Alamelu. According to him, Pooja looks like his lover Alamelu and Guru Moorthi finally seduces her. They decide to get married but the day before their wedding, he foists prostitution charges on her and she is arrested. Guru Moorthi, in fact, is a mechanic living in both Vishakhapatnam and Chennai. Shanti (Kushboo), a petty thief, steals money to bring up her two nephews. She befriends Guru Moorthi and he accommodates her in his house. They both fall in love and Shanti is renamed Sonali by Guru Moorthi. They get married at the register office and Shanti signs under the name Sonali. One day, Guru Moorthi cancels the wedding of a woman named Sonali (Madhu Sharma) and he claims to be her husband, to prove it, he shows his marriage certificate. His wife Shanti doesn't understand why he behaves like a sadist and she was ready to leave him. Guru Moorthi ultimately tells her about his bitter past.
In the past, Mahendra Boopathi, despite being a young gold-medalist graduate, was unable to find a work. He lived with his mother, his sister Kalyani and his maternal uncle Nagarajan (Manivannan). His neighbour Priya (Anju Aravind) fell in love with him and she decided to live in his house without getting married. Boopathi had a chance to get a job in a bank if he passed an exam. On the day of the exam, he inadvertently lost his hall-ticket. In the meantime, Pooja, Sonali and Indhu (Indhu) were attacked by the rowdy Kaali (Thalaivasal Vijay) and they killed his younger brother accidentally. The police pressured them to tell the truth, they then found Boopathi's hall-ticket at the crime scene and they blamed him for killing Kaali's younger brother. Guru Moorthi was immediately arrested. Later, Kaali's elder brother Vijay (Thalaivasal Vijay) killed Guru Moorthi's entire family and his lover Priya. Guru Moorthi was sent in jail for 7 years and Kaali fled to Ooty. Kaali changed his appearance, his name and he became a successful businessman. Hence, only Guru Moorthi and his uncle Nagarajan were the people to survive the attack on his family.
Back to the present, Shanti feels sorry for her innocent husband and decides to help him in seeking his revenge and calming himself. Guru Moorthi thus now searches for Kaali and Indhu. Kaali is now married to Indhu and they have a girl. In the end, Guru Moorthi tricks Indhu into shooting Kaali to death for which she gets arrested and Guru ends up adopting Indhu's daughter as his own.