A tender romance blossoming in Kolkata between law student Ramesh and his friend's sister Hemnalini is nipped suddenly when his father sends an urgent and mysterious summons from his village home. There, the dutiful son is peremptorily ordered to marry Susheela, daughter of a hapless widow. Ramesh refuses, confesses that his heart belongs to another. But the widow's fervent plea softens him ultimately. And he concedes, albeit with a heavy heart. The wedding takes place with due ceremony; and Ramesh sets out with his bride on a river boat journey back to Kolkata.
Soon a fierce storm arises; the boat tosses helplessly and finally capsizes in the churning waters. Later that night, Ramesh comes to his senses on a deserted shore under a starlit sky. Some distance away, he sees the unconscious form of a young bride. Her pulse is still beating, and in response to his voice calling 'Susheela' she opens her eyes at last. There is no one else in sight, alive or dead. The two move off, take a train to Kolkata, the bride wondering why they were not going to Kashi, but trusting his judgment implicitly.
Hem, his true love, knows nothing of all this. Ramesh has been missing from the evening of her birthday party. They have learnt of his hasty departure from the city, but nothing else. Though she pines inwardly, she is confident that he will return soon.
Back in Ramesh's new home in Kolkata, the facts of mistaken identity gradually come to light. She is Kamala not Susheela. Her husband is a doctor named Nalinaksha Chatterjee. Ramesh writes an advertisement to trace his whereabouts; but he does not have the heart to break this news to the helpless trusting young girl in his care. He puts her into a boarding school instead. But soon, Hem's would be suitor Akshay comes to know of Ramesh's secret and brings proof positive to Hem. Ramesh, unable to handle such a scandal, seeks hiding in Gorakhpur with Kamala.
A devastated Hem is brought to Kashi by her father to help her forget. There she meets Nalinaksha and they warm up to each other.
Kamala in the meanwhile having read the advertisement in an old newspaper, realizes the enormity of the lie she has been living, and walks out determined to drown herself in the river. Ramesh returns and finds her suicide note, searches everywhere to no avail. He does not know that she has been rescued by a courtesan and deposited in Kashi under Nalinaksha's mother's care. Kamala now sees her real husband for the first time, but cannot speak up, for he is betrothed to Hem.
Finally, the advertisement she keeps knotted in her saree is discovered, and the whole truth comes to light. Ramesh finally traces Nalinaksha and arrives at his house.
The whole sorry mess raises many questions of head and heart and the validity or otherwise of social conventions. We are left wondering whether true love will finally triumph.