Chhoti Bahu is a family drama that upholds human relationships over all other emotions. It shows the triumph of love over everything else and also shows that maternal love need not always come from the biological mother.
Radha and Madhu are a newly married couple and very soon after marriage, much to the shock of Madhu, it is revealed that Radha is a patient of epilepsy. Her guardians claim that doctors had said that the seizures would cease soon after wedlock. It is seen that Radha is seized by the attacks only in situations of mental pressure. When Radha's special fondness for children is noticed, Seeta and her husband(Madhu's elder brother and sister-in-law) gladly make Radha the foster mother of their son Gopi. Radha is only too happy with the new responsibility. She takes care of the little boy just like her own son. The family lives in happiness nurturing traditional values of respect and affection. When Madhu's medical practice flourishes, the younger couple force the elder brother to give up his job because the latter and his wife have toiled very hard in order to make Madhu a successful doctor in the absence of their parents. Gopi is also growing up happily enjoying the love of his surrogate parents as well as his real parents.
Everything seems to run well for the family till Madhu's sister Paro comes over with her son and husband for good. Her husband is terrified of her and she has spoilt her son Nikkoo. He is a persisitent failure in his school and has run into bad ways. Being of a similar age, Nikkoo and Gopi become fast friends and it is not long before the latter gets influenced by the former's wrong habits. Successive cases of wrong conduct in school raises Radha's ire and she decides to teach Gopi a lesson.
Gopi realises his mistakes and turns to Seeta for shelter. In a war of words between the two sisters-in-law, Seeta casually refers to Gopi as "her son" which complicates matters further. Radha feels deprived of her rights on Gopi and she retorts back. The argument takes up greater proportions owing to Paro's vicious interferences. She aims at Radha's disownment of Gopi and adoption of Nikkoo. To make matters worse, she succeeds in maligning the tender mind of the innocent Gopi. Matters come to a head and Radha leaves the household. She goes back to her maiden home where she vows not to touch a morsel of food or water. The extended family realise the seriousness of the situation and rush to see her. Paro's evil intentions are exposed and peace is restored between Gopi and Radha and the family go back to their own homes to live in happiness.