Set in a prison in pre-Independence India, the film opens with Kalyani (Nutan), who is serving a life sentence for murder, telling a jailmate her story. Kalyani is the daughter of a respected postmaster (Raja Paranjpe) in a Bengal village in the 1930s. She is in love with freedom fighter Bikash (Ashok Kumar), who leaves the village but promises to return. Kalyani waits for him, but after a while the taunts she and her ageing father have to suffer become unbearable. Miserable, Kalyani moves to the city and starts working at a hospital where she has to look after a cantankerous woman who turns out to be Bikash's wife. One day, Kalyani learns that her father has died in an accident on his way to the city. The shock triggers temporary loss of sanity. Alone in her world of suffering, Kalyani suddenly identifies Bikash's wife as the cause of her troubles and poisons her. In prison, jail doctor Deven (Dharmendra) falls in love with Kalyani though she carefully avoids him. After her release from prison for good behaviour, as she proceeds to Deven's home to start life anew on the advice of the jailor Mahesh Chandra (Tarun Bose), Kalyani comes across Bikash at a junction. Bikash has become a consumptive, and Kalyani learns, from an accompanying relative, how he was forced to forsake his love for the sake of the freedom struggle. The revelation leaves Kalyani on the horns of a dilemma.