Gayathri, a docile Brahmin girl, is married to Ganesh, a conservative Brahmin. Gayathri suffers from a fear psychosis and gets frightened of even small things. They are a happy couple with an infant daughter Alamelu. Once Gayathri attends an interview and returns home dazed. From then on, her behaviour becomes abnormal and unpredictable, which affects her family life. Slowly, she loses her mental balance and people around her, including her child, husband and mother-in-law, are afraid to come anywhere near her. Nobody is able to comprehend the basis for her erratic behaviour and all efforts to get her treated fail. She accidentally kills her child, after which Ganesh's mother advises him to divorce her and remarry, and he relents. Gayathri is taken back to her parents’ home by her father. Ganesan marries Jayanthi, the daughter of advocate Ananthu, on the persuasion of his mother.

Jayanthi learns about Ganesh's first marriage and subsequent divorce only after the wedding. Though Jayanthi is initially upset, she gets reconciled. The mentally imbalanced Gayathri keeps visiting Ganesh's house even after their divorce. One day, she barges into their bedroom and attacks Jayanthi when she is intimate with Ganesh. An upset Ganesh advises Gayathri's father to move her out of town and he complies. Jayanthi gives birth to Ganesh's daughter Rukmini. Gayathri's life takes a new turn in the new town. An unknown person attempts to kill her when she is alone; she fights him and gets injured in the process. As a result, she regains her memory and sanity, and recollects what happened to her.

Gayathri reveals to her parents that what she went through and why she behaved in an unpredictable manner. On the day she was returning from the interview, she witnessed a person murdering a girl in an isolated bungalow. Since Gayathri was the only witness, the murderer chased her and attempted to kill her. In the process, she lost her mental balance out of fear. Her parents become happy with her return to normalcy. She understands the changed scenario of her life, including the death of her child and divorce, and reconciles to live alone. She takes up a job and refuses to collect further alimony from Ganesh.

Rukmini is kidnapped by Kandappan, who previously worked as Jayanthi's driver and had fallen in love with her. Ananthu had implicated Kandappan in a false case and got him arrested to keep him away from Jayanthi. Exploiting Kandappan's absence, he got Jayanthi married to Ganesh. To take revenge, Kandappan has kidnapped Rukmini and demands that Jayanthi have sex with him for getting her child back. Jayanthi reaches his place and prays for her escape with the child. At the same time, Gayathri, who learns about the kidnapping from her mother-in-law, reaches the spot. She recognises Kandappan as the murderer. After becoming possessed by goddess Bhadrakali, she fights Kandappan who ultimately dies after being impaled. Gayathri, who was also injured, succumbs in Ganesh's arms after having saved his daughter.