This socially relevant romantic drama revolves around Ratan, a sincere and conscientious young man.
During his childhood, Ratan's best friend was Sona and the youngsters held the belief that they would grow up and get married. However, while on a trip to the Ganges, Sona is kidnapped and despite their best efforts, Ratan and his family members are unable to locate her.
Many years pass and Ratan begins working in the big city of Calcutta. On one fine day, he has the strong feeling of having had a glimpse of Sona near a shop and despite the objections of his friends, he decides to investigate and find if his instinct was correct.
To his horror, he finds that his childhood sweetheart has become a dancer by the name 'Banarasi' and lives amidst other courtesans in the red light district of the city. Against all tradition and societal norms, Ratan promises to marry her. They elope and begin living a quiet and contented life far away from the city, where nobody knows anything about their true identities or Sona's past.
As the wife of a respectable man, Sona is treated with respect and dignity by all in the new milieu. Will they succeed in keeping the past at bay, or will it return to haunt them? How will Sona be treated if the truth about her past were to be revealed? Will the loving couple succeed in staying together against all odds?