Kalyanam is the naïve, infantile son of Chinnadurai, a wealthy tea estate owner. Realising his son would not be able to manage the estate or even take care of himself after his death, Chinnadurai tries to get him married but Kalyanam does not like the prospective bride. Kalyanam is in love with Shenbagam, a woman who works on the estate and is the daughter of Chinnadurai's driver Perumal. Along with his young friend Kuppu, Kalyanam tries to court Shenbagam but she does not reciprocate his feelings.

The manager of the estate is trying to seize Chinnadurai's wealth and property. He conspires with Perumal and the cook Samipillai, and hires a goon to kill Chinnadurai. On his deathbed, Chinnadurai tells Kalyanam he abandoned his first wife Rajalakshmi and Kalyanam's twin brother Raman in Madras, and advises him to go there to escape the malicious employees. Kalyanam reveals this plan to Samipillai, who leaks it to the manager. Samipillai tells Kalyanam he will fetch Raman and Rajalakshmi himself, and hires actors Kittu and Rangamani to pose as them.

Kalyanam overhears the gang laughing at how they duped him and runs to inform the police but the gang corner and murder him. Shenbagam watches the killing and becomes mentally unstable. The gang cuts off the other witness Kuppu's tongue, rendering him mute. The gang try to seize the property but they face difficult legal formalities from the bank. Kalyanam, who has become a ghost, travels to Madras to locate his brother and mother. He finds Raman and tells him what happened. Rajalakshmi confirms to Raman he had a twin, and he decides to take revenge.

Raman arrives at his late father's estate, and exposes Rangamani and Kittu as frauds, who now claim to be the stepmother and Kalyanam. Raman poses as Kalyanam's ghost and threatens Samipillai, who breaks down, apologises and joins Raman in his crusade. With the help of Kalyanam, Raman restores Shenbagam's sanity, teaches Kuppu to read and write so he can testify. The manager and his gang try to kidnap Rajalakshmi, who had arrived at the estate sometime before, and attack Raman. Kalyanam temporarily enters Raman's body and gives him the power to fight everyone. The manager and his gang are arrested due to Kuppu's testimony. Raman and Shenbagam marry.