Binodini, a young widow is forced to live in Calcutta with Rajlakshmi and her son, Mahendra, who had rejected a former marriage proposal with her. Mahendra now gets attracted to Binodini even though he is already married to Ashalata.
Mahendra's mother wanted him to marry Binodini, her friend's convent educated daughter. But Mahendra refused. Then his mother requested Bihari, Mahendra's best friend to marry Binodini and which Bihari refused too. Eventually, Binodini got married and gets widowed. Meanwhile, Mahendra married Ashalata, a poor orphan uneducated girl whom Bihari secretly fancied. Mahendra was besotted with his wife when Binodini came to live in their house.In a bout of jealousy and revenge, she forms a bond with Ashalata and calls each other Choker Bali (grain of sand). With time, an extra-marital relationship develops between Mahendra and Binodini, which threatens to destroy his marriage. But, soon Binodini discovers that Mahendra is a self-obsessed person, unable to provide a safe shelter to her. So she inclines towards Bihari, who lives life by principles. In the end, Bihari falls in love with Binodini and when he realizes her feelings for him, he proposes her for marriage. Would Binodini accept the proposal?
