Sivaji Ganesan, B. Saroja Devi, Sowcar Janaki
Sivaji is a doctor searching for a cancer cure. Saroja Devi is Sivaji's nurse who assists him in his research. Sivaji offers to marry her after her father's death. After putting in enormous efforts, Sivaji emerges successful in formulating a new drug but Saroja Devi is diagnosed with tuberculosis. Sivaji begins to neglect his duties as a doctor, focusing on Saroja Devi's health. Saroja Devi flees on a train as she does not wish to divert him from his research.
The train crashes and Saroja Devi is believed to be dead. Sivaji is heartbroken but vows to complete his research. Sivaji's family forces him to marry Janaki, but they do not have a happy home life, as he is more oriented towards his research than his family. Janaki and Sivaji fight, and in one of these fights Sivaji loses his eyesight. Meanwhile, Saroja Devi escapes the train crash and goes to Switzerland to cure her tuberculosis. Saroja Devi returns from Switzerland to find that her husband has lost his eyesight. She offers to nurse Sivaji; Sivaji finds her voice familiar but does not recognize her, and confides in her that he is still fond of his ex-wife. Janaki overhears this, and complains to her parents. Saroja Devi faces criticism from the womenfolk of the house for her intimacy with Sivaji.
Sivaji's brother(acted by Prem Nazir) grows fond of Saroja Devi and tells Sivaji so. Sivaji suggests they marry. Saroja Devi is upset and reveals her identity to Sivaji's family. Sivaji's sight is restored by an operation. He recognizes Saroja and rushes to the marriage hall to find that Saroja Devi's sister is married to his brother. Sivaji reunites with Saroja while Janaki joins the Red Cross and flies to Switzerland. The movie ends with Sivaji and Saroja Devi working together to benefit mankind.