The plot is simple. A widowed mother (played by Kovai Sarala) has two sons -- the elder son (played by Sriman) is an architect while her younger son Raghava (played by Raghava Lawrence) is a vagabond who does nothing but play cricket. Sriman and his wife (played by Devadarshini) are happily married and have two kids. Raghava, who is scared of evil spirits, is in love with Priya (played by Lakshmi Rai), who happens to be his sister-in-law's sister.
Life seems to be a bed of roses for this joint family until the day Raghava and his friends choose to go to a new plot of land to play cricket. The spirits of three bodies buried in that patch of land follow Raghava to his home and there starts the problem.
Initially, it is only Kovai Sarala and Devadarshini who realize that something is amiss. They seek the help of a priest who asks them to carry out three tests to ascertain if there is an evil spirit in their home. After sending everybody else in the family away from their home under one pretext or the other, the two carry out the tests which prove that there are evil spirits.
They turn to the priest again for help. However, he claims that he does not deal with driving away evil spirits and that they must seek the help of others specializing in the task. The two end up seeking the help of two conmen posing as specialists in occult sciences (played by Manobala and Mayilsamy). After collecting a huge sum as fee, the conmen tell the women that they’ve captured the spirit inhabiting their home and that they can now resume their normal lives.
The family resumes its daily routine trusting the conmen’s words. However, Raghava’s behavior begins to undergo a change. He starts dressing like a woman and expresses a desire to use those products used by women. His behavior gives rise to suspicion and one night, when the family members can take it no more, they confront him only to come face to face with three evil spirits that are using his body as a medium to fulfill their wishes.
Shocked, they seek the help of holy men at a Dargah to get rid of the spirits. When one of the holy men finally threatens to destroy the spirits, they come out of the body of Raghav and narrate the story of Kanchana(played by Sarath Kumar), a transgender. The spirits tell the holy man that they are there to take revenge on an MLA and two of his cronies for the grave injustice he meted out to them.
The holy man, after listening to the story of the spirits, is moved but refuses to help them. He binds them in a box and throws the box into the sea. He also gives a sacred thread to Raghava asking him to wear it at all times for the next three days. However, Raghava has other plans. What was the grave injustice meted out to the spirits by the MLA and his cronies? Does Raghava help the spirits gain their revenge? The film answers all these questions in a convincing manner.
Both Lawrence and Sarath Kumar have done a good job in the film. Kovai Sarala, Devadarshini and Sriman add to the fun factor. Lakshmi Rai has taken care of the glam quotient. None of the songs in the film make the cut, save the last one. One can only say Thaman’s talent has been wasted. The movie has its share of thrills and laughs. On the whole, Kanchana is an entertaining affair and can be watched once.