Ravi is a doctor searching for a cancer cure. Shanthi is Ravi's nurse who assists him in his research. Ravi offers to marry her after her father's death. After putting in enormous efforts, Ravi emerges successful in formulating a new drug but Shanthi is diagnosed with tuberculosis. Ravi begins to neglect his duties as a doctor, focusing on Shanthi's health. Shanthi flees on a train as she does not wish to divert him from his research.

The train crashes and Shanthi is believed to be dead. Ravi is heartbroken but vows to complete his research. Ravi's family forces him to marry Nalini, but they do not have a happy home life, as he is more oriented towards his research than his family. Nalini and Ravi fight, and in one of these fights Ravi loses his eyesight. Meanwhile, Shanthi escapes the train crash and goes to Switzerland to cure her tuberculosis. Shanthi returns from Switzerland to find that her husband has lost his eyesight. She offers to nurse Ravi; Ravi finds her voice familiar but does not recognise her, and confides in her that he is still fond of his ex-wife. Nalini overhears this, and complains to her parents. Shanthi faces criticism from the womenfolk of the house for her intimacy with Ravi.

Ravi's brother Sekar grows fond of Shanthi and tells Ravi so. Ravi suggests they marry. Shanthi is upset and reveals her identity to Ravi's family. Ravi's sight is restored by an operation. He recognises Shanti and rushes to the marriage hall to find that Shanthi's sister is married to his brother. Ravi reunites with Shanti while Nalini joins the Red Cross and flies to Switzerland. The movie ends with Ravi and Shanthi working together to benefit mankind.