In a village, a group of people are led by Ayyanar in cleaning a palace whose owners plan to sell it. During the night, the cook is frightened by some supernatural being in the palace and disappears.

The next day, an estranged Eshwari returns to the village with her husband and son Muliankannan, along with her older brother and his daughter Maya. The pair, along with their late elder brother's son Murali and his new wife Madhavi, have gathered to sell their palace off to Ayyanar. Meanwhile, Paalsamy sneaks into palace under the guise of a cook, to find a photo that is the sole evidence that he is also an heir to the palace, so he can claim his share of the money.

Strange events begin to happen during their stay at the palace. Madhavi sees a servant's daughter talking to a mysterious girl called Selvi who no one else can see. The girl's mother explains that she is mentally impaired. Mishaps continue to happen, delaying the sale of the palace and the family extend their stay. Meanwhile, two other servants have also gone missing. Now Ravi, Madhavi's elder brother, comes to the palace to meet his sister. Later, Madhavi and Maya tell Ravi of the strange happenings, so Ravi sets cameras up around the palance with Maya's help.

While watching the camera feed, Ravi sees a worker backing away from something, but the camera's feed suddenly dies. At the same time, a fortune teller in front of the house runs away in terror after seeing something. The next day, the bodies of the missing servants found by the cops in a local pond. Ravi is shocked and visits the fortune teller, who reveals he witnessed a worker being killed by a woman possessed by a vengeful spirit. The fortune teller gives him an egg and tells that when the possessed person is near the egg, it will start spinning. To Ravi's horror, the egg reacts to Madhavi.

Since the little girl always speaks of a woman named Selvi, Ravi sets out to investigate. Ayyanar becomes angry when mentioned about Selvi, who stole the temple's jewels and ran away from the village. However, Selvi's friend Ramya tells Ravi that Selvi was a good person and not a thief.

A few years back, prior to his marriage, Murali came to the village and fell in love with Selvi. Selvi also liked him, but she is a girl who is often possessed by the goddess and predicts the future. Wishing to maintain her holiness, and wary of the difference in their statuses and lifestyles, she is reluctant to accept his confession. On the day Murali planned to leave the village, he asked her to meet him at the palace if she wanted to leave with him. With Ramya's encouragement, Selvi leaves to confess her love to Murali, but disappeared before reaching him.

As per Ravi's plan, Ramya comes to meet the possessed Madhavi. Selvi, recognising Ramya, tells her all that happened that day. It had been Ayyanar and his friends who had stolen and replaced the temple jewellery with fakes. When Selvi had touched one of the fakes, she received a premonition, and confronted the culprits. When they attacked her, she fled to Murali, but narrowly misses him. Ayyanar and his accomplices, the dead servants, killed and buried her inside the palace.

Selvi tells Ramya that she intends to live on with Murali in Madhavi's body. As that day is an auspicious day, if she gets intimate with Murali, no one can ever drive her out of Madhavi's body. If they cannot consummate their relationship, she will kill Murali, so that they will be together in death.

After hearing the story, Ravi meets a priest, who says there are only 2 ways to stop Selvi: use a strong emotion to bring Madhavi to her senses, or bring Murali to the river junction where a holy ritual will take place, generating a powerful energy that will lay Selvi to rest. Selvi's attempts to become intimate with Murali is being disrupted by the inhabitants of the palace, while Ravi attempts to find a way to bring Murali to the river junction without tipping off Selvi. Meanwhile, Selvi puts Murali into a trance so that she can track down and kill Ayyanar.

While she is gone, the priest and Ravi try to bring Murali out of his trance and take him to the river, but Selvi returns and attempts to stop them. The priest traps her in a circle of fire and Ravi flees with Murali. Selvi escapes and follows them, and Ravi's car overturns and falls into the river. Selvi tries to drown Murali, but Ravi tells Madhavi is pregnant and brings her to her senses briefly. At the same time, the rituation is completed, and its power finally severs Selvi's possession.

No longer possess Madhavi, Selvi disappears and Madhavi and Murali reunite. Ravi also unites with Maya in the end. And when they all pose for a photograph in front of the palace, a zoomed-in shot shows a ghostly figure moving near a window in the palace, implying that Selvi has returned to the palace.