The film starts with a fight between two teenagers where one of them is hit on the head and faints. The scene then shifts to the house of Gnanamoorthy (Sathyaraj), a politician in the Mettupalayam district, who lives with his wife Padma (Seetha), daughter Parvathy (Jyothika), and his mother (Sowcar Janaki). Parvathy spends her days in sorrow, hoping that her aggressive younger brother Saravanan (Navneeth Madhav) would return home, who had left the house 15 years ago. Her family too believes that the miracle may happen one day.

One day, Moorthy receives a call from Jeevanandam (Ilavarasu), who tells him that his long-lost son is found. Moorthy finds out that his "son" is Vicky (Karthi), a trickster and tourist guide in Goa. Moorthy takes Saravanan back to his house, where Padma is elated at seeing her son. However, Parvathy does not show any affection and keeps shunning Vicky. Later, it is revealed that Jeeva and Vicky had put a plan that Vicky would act as Saravanan for a while and would steal some money and escape. Jeeva and Vicky would then share the bounty. Saravanan's friend Karan (Anson Paul) doubts that Vicky is actually Saravanan, and his doubts are confirmed when he asks Vicky about their childhood. Meanwhile, it is revealed that Moorthy is actually the one who had made Jeeva make Vicky act as Saravanan. When Jeeva blackmails Moorthy for two crores, Moorthy kills Jeeva and puts the blame on Manimaaran (Bala), a local politician who wants to build a resort in the nearby village.

Karan doubts Vicky in his involvement in the murder since he shows up at Jeeva's house to remove the evidence that he is a fraud. Karan doesn't find any evidence tying Moorthy or Vicky to the murder and arrests Manimaaran. It is revealed to the audience that Moorthy had entered the house once again and removed all the evidence. While Vicky is driving around in a car, he is hit by a lorry and narrowly escapes death. Another attack in the house confirms his suspicions that someone is trying to kill Saravanan and sets out to find what really happened to Saravanan. After tracing Saravanan's steps that night, he finds the lorry that hit him and on interrogating the driver, it is revealed that the perpetrator is Moorthy's right-hand man Sudhakar (Hareesh Peradi), who was angry that Saravanan had come back and he would lose the position of MLA to Saravanan.

Finally, from a clue by Saravanan's girlfriend Sanjana (Nikhila Vimal), Vicky deduces that Saravanan had come back (he had fought with his mother and sister and was the reason for Moorthy's mother's condition) and in the anger that Saravanan was the cause of his mother's paralysis, Moorthy had killed him accidentally and used the sympathy to earn votes. On confronting him, Moorthy gives Vicky money to keep the matter quiet, but Vicky tells Padma, who is also aware of the truth. Finally, Parvathy holds Vicky at gunpoint and reveals the truth.

After Saravanan had fought with his mother and sister, Padma and Parvathy take Moorthy's mother to the hospital. Moorthy comes to the house and sees Saravanan. In a fit of rage, he keeps beating Saravanan, but when Saravanan hits him back in a drug-fueled rage, Moorthy breaks down. Parvathy tries to console her father and finds that Saravanan was doing drugs. She throws the drugs away, and Saravanan tries to choke her. In desperation, Parvathy grabs the nearest weapon and accidentally slits his throat, and Saravanan dies. In order to save his family's reputation, Moorthy fabricates a story where Saravanan had run away. Shocked at the revelation, Vicky decides to leave the house, and at the train station, Parvathy says that she had really accepted Vicky as her brother. The film ends with Vicky/Saravanan and Parvathy driving back to their home.

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