The story is about Hiraman, a rustic villager from a remote village in Araria (Bihar), who drives a bullock cart to earn his livelihood. The story begins with Hiraman taking two consecutive vows based on the difficult situations he had to undergo, before he meets a nautanki dancer, Hirabai. The story soon transforms into the story of the friendship between a bullock cart driver and an urban nautanki dancer. The movie, finally, ends with Hiraman taking the third vow. Hiraman is a bullock cart driver with conservative traditional values. While smuggling illegal goods on his bullock cart and close escape from police, Hiraman takes vow (first Kasam) to never carry illegal goods again in his cart. While transporting bamboo for timber trader on his bullock cart, he is beaten by two men when their horses are upset by bamboos of Hiraman's cart. After that incident, Hiraman takes another vow (second Kasam) to never carry bamboo again in his cart. One night, Hiraman is asked to carry Hirabai, a nautanki dancer as a passenger to the 40 miles distance to the village fair. As they travel together Hiraman sings to pass time and tells her story of the legend of Mahua. As the journey progresses, Hirabai is mesmerized by Hiraman's innocence and his simple philosophy of life. Hiraman in return sees her as an angel of purity. Once they reach the village fair, Hiraman joins with his band of bullock cart drivers and Hirabai joins the nautanki company. Hirabai asks Hiraman to stay at village fair for a few days to see her dance. Hirabai arranges free passes for Hiraman and his friends to see nautanki on every night as long as village fair runs. As Hiraman attends nautanki, he becomes aware that other people see her as a prostitute and it disturbs him. He tries to shield and protect her from society. The bond between two grows stronger as the days pass at the fair. He gets involved in fights with local people who speak badly about her and her profession. Hirabai tries to make him understand the harsh reality of her life. Hiraman asks her to leave her profession and start living a respectable life. Hirabai refuses to leave her acting career. Depressed, Hiraman leaves village fair and returns to his village. In the mean time, Hirabai understands Hiraman's unselfish love. Hirabai meets Hiraman and reveals her past secret that she had been already sold and she was no longer a virgin beauty. Hirabai returns to her hometown. After seeing Hirabai going away from his life, Hiraman takes third vow (teesri Kasam) to never carry a nautanki company dancer again in his cart.