Mutiyar is the story of visionary woman Satya (Reeta Bhaduri) who dreams of a social set-up free from the bane of social inequalities. She expresses her revolutionary views through songs at college functions and becomes the darling of the students. All the teachers appreciate her frankness and vision to herald an era of social upliftment. She belongs to a poor family and her father is bedridden. She cycles to college and once while returning home, she is intercepted by the village goon Jaggu (Yash Sharma). She gathers sufficient courage to free herself from his clutches. Her father is worried about her as she toils hard attending college in the day and earning a livelihood by tailoring clothes at night.
Seth Deen Dayal (Rajan Haksar)’s forefathers had grabbed the lands of poor tillers in lieu of the petty loans which they could not repay. Apparently the rich and immoral Deen Dayal had squandered all his ill-gotten wealth on women and wine neglecting his wife (Sudha Chopra) and son Bobby. His sharp eyes are always in search of prey and one day he offers Satya a job in his office. He asks his secretary Shobhna (Kamal Hans) to bring Satya for his entertainment. Satya, however, defies his schemes and leaves the job.
Satya and Deen Dayal’s younger brother Chander (Satish Kaul), who studies in the same college, fall in love. When Satya comes to know that Chander is Deen Dayal’s brother, her love dwindles. She has always been persuading the villagers to forcibly snatch their rights from Deen Dayal. Deen Dayal cannot tolerate this outburst. Deen Dayal wants to grab a fat dowry by marrying Chander to Meena (Saibi Oberoi), daughter of a rich man Lala (Ranjit Sood). He asks Chander to forget Satya and give his consent for this marriage proposal. Instead, Chander leaves the house and goes to Satya’s village to devote his time and energy for the benefit of the villagers. Infuriated by the success of Satya in uniting the villagers, Jaggu and his associate Rangila abduct Satya. Chander and Menhga fight with the gangsters and save Satya’s honour. The villagers overpower Deen Dayal and his men. In the scuffle, a bullet hits the son of Deen Dayal (Bobby) who is gravely injured. Immediate blood transfusion is required. Satya’s blood sample matches and she donates blood to save Bobby. This kind act of Satya moves Deen Dayal’s heart. He repents for his misdeeds and accepts Satya’s hand for Chander in marriage.