The film is set in a prison in around 1934 in pre-Independence India, where Kalyani is serving life imprisonment prison for committing a murder, and we learn the circumstances of her crime in flashback as she divulges it to the jailor. The film is set in Bengal in the 1930s, during the British Raj, where Kalyani (Nutan) is the daughter of the postmaster (Raja Paranjpe) of the village, who falls in love with a freedom fighter, Bikash (Ashok Kumar), who later leaves her in the village promising to come back but never does. Society treats them harshly. Broken by her father's misery and that of her own, Kalyani moves to the city, to the singing of the sad song "O Jaanewale Ho Sake To Laut Ke Aana". In the city, she works as a caretaker of an obnoxious and mentally unstable woman, who turns out to be the wife of Bikash. Kalyani learns that her father came to the city looking for her and died in an accident. That prompts her to poison her lover's wife, identifying her as the cause of her miseries in a moment of insane rage. Director Bimalda captures her emotions as she resolves to commit the crime, with light and darkness falling on her face due to a welder's torch and the thumping of iron in the background, and the ambient sounds as she inches towards the decision, pumping vigorously into a kerosene stove, without uttering a single word through it all. And subsequently confesses to the crime with equal passion.