Rajinikanth, Prabhu, Jyothika, Nayantara
Saravanan (Rajinikanth), a psychiatrist, visits India on vacation. He meets up with his foster brother Senthilnathan, alias Senthil (Prabhu), and his wife Ganga (Jyothika). Senthil's mother Kasthuri (K. R. Vijaya) wanted Senthil to marry Priya (Malavika), daughter of his father's cousin Kandaswamy (Nassar), to reunite the two branches of the family after 30 years of separation because Senthil's father (Sivaji Ganesan) chose to marry Kasthuri instead of Akhilandeshwari (Sheela), Kandaswamy's sister. Saravanan learns that Senthil had bought the Vettaiyapuram mansion, despite attempts by the local village elders to dissuade them, and moves in with them. Akhilandeshwari is jealous of Saravanan and plots to kill him with the help of her assistant Oomaiyan (Sonu Sood).
When the family visits a temple, the chief priest reveals the reason everyone fears the Vettaiyapuram mansion. A hundred-and-fifty years before, a king named Vettaiyan travelled to Vijayanagaram in Andhra Pradesh, where he met and fell in love with a dancer named Chandramukhi. However, she did not reciprocate his feelings as she was already in love with a dancer named Gunashekaran. As a result, Vettaiyan took her back to his palace by force. Unknown to him, Chandramukhi made Gunashekaran stay in a house nearby and had meetings with him secretly. When Vettaiyan discovered this, he beheaded Gunashekaran on Durgashtami and burnt Chandramukhi alive. As a result, Chandramukhi's ghost tried to take revenge on Vettaiyan, who with the help of various priests and sorcerers from all over the country, tames the ghost by locking it up in a room located in the palace's south-west corner. Later, Vishwanathan (Vineeth), a dance professor, and Priya's love is supported by Saravanan, who asks Kandaswamy to arrange their marriage.
After hearing Chandramukhi's story, Ganga, who thinks that the story was fabricated to scare thieves from stealing treasures in the room, wants to go there. She gets the room key from the gardener's granddaughter Durga (Nayantara) and opens the door. Subsequently, strange things begin to happen in the household; a ghost frightens the people in the house, things inexplicably break, and Ganga's sari catches fire. Suspicion turns towards Durga. Senthil calls Saravanan to solve the case. As soon as Saravanan returns, a mysterious being tries to kill Priya. Attempts to kill Senthil are made with poison and by pushing a fish tank. A mysterious voice sings during the night. Saravanan investigates these incidents.
Ganga mysteriously disappears during Priya and Viswanathan's wedding reception. Saravanan notices her absence and searches for her, but he is almost killed by Oomaiyan—who has been sent by Akhilandeshwari. Saravanan subdues Oomaiyan and with Senthil's help finds Ganga, who is supposedly being sexually harassed by Viswanathan. Saravanan reveals to Senthil and Viswanathan that Ganga suffers from split personality, how she became affected by it and how she took up Chandramukhi's identity. He tells them Ganga tried to kill Priya and Senthil, and to frame Viswanathan for sexual harassment because from Chandramukhi's view, Viswanathan is her lover Gunashekaran because he stays in the same home as Gunashekaran. The only way to stop this from happening is to make Ganga believe Saravanan is dead because Saravanan acted like Vettaiyan and disrupted one of the pujas conducted by the exorcist Ramachandra Acharya (Avinash) by conversing with the ghost in order to know its wish.
Akhilandeshwari overhears Saravanan's idea of self-sacrifice and apologises to him. Later, in the dance hall, the family and Ramachandra Acharya allow Chandramukhi to burn Saravanan alive. Ramachandra Acharya blows smoke and ash on Ganga's face when she is given a torch to burn Saravanan. Senthil then opens a trapdoor to let Saravanan escape, and an effigy of Vettaiyan gets burnt instead. Convinced that Vettaiyan is dead, Chandramukhi leaves Ganga's body, curing her. The two families are reunited after 30 years; Saravanan and Durga fall in love, and Swarna (Suvarna Mathew) and Murugesan (Vadivelu) become parents after eight years of marriage.