The film is set in 1957, the present day at the time of shooting. When construction of an irrigation canal to the village is completed, Radha (Nargis), considered to be the "mother" of the village, is asked to inaugurate the canal. She remembers her past, when she was newly married.
The wedding between Radha and Shamu (Raaj Kumar) is paid for by Radha's mother-in-law, who borrows the money from the moneylender Sukhilala. This event starts the spiral of poverty and hardship that Radha endures. The conditions of the loan are disputed, but the village elders decide in favour of the moneylender, after which Shamu and Radha are forced to pay three quarters of their crop as interest on the loan of INR500 (valued at about US$105 in 1957). While Shamu works to bring more of their rocky land into use, his arms are crushed by a boulder. Ashamed of his helplessness and humiliated by his fellow villagers, Shamu decides that he is of no use to his family and permanently leaves Radha and their three sons. Soon after, Radha's mother-in-law dies.
Radha continues to work in the fields with her two elder sons and gives birth again. Sukhilala offers to help alleviate her poverty if she marries him, but she refuses. A severe storm and the resulting flood destroys houses in the village and ruins the harvest; Radha's youngest son dies. Although the villagers begin initially to evacuate the village, they decide to stay and rebuild it, persuaded by Radha.
The film skips forward several years to when Radha's two surviving children, Birju (Sunil Dutt) and Ramu (Rajendra Kumar), are young men. Birju, embittered since childhood by the demands of Sukhilala, takes out his frustrations by pestering the village girls, especially Sukhilala's daughter, Rupa. Ramu, by contrast, has a calmer temperament and is married soon after. Birju's anger finally becomes dangerous and, after being provoked, he attacks Sukhilala and his daughter and steals Radha's kangan (marriage bracelets) that were pawned with Sukhilala. He is chased out of the village and becomes a bandit. Radha promises Sukhilala that she will not let Birju cause harm to Sukhilala's family.
On Rupa's wedding day, Birju returns with his gang of bandits to enact his revenge. He kills Sukhilala and kidnaps Rupa. When he tries to flee the village on his horse, Radha, his mother, shoots him. He dies in her arms. The film returns to 1957; Radha opens the gate of the canal and its reddish water flows into the fields.