Bihari's (Om Shiv Puri) father loses all his property in gambling and alcohol. He exchanges his own son Ajay (Ranjit) with a rich family's son Kishan (Rajesh Khanna).
On the other hand, Shamsher Singh (Kader Khan) murders the Maharaj of Chandpur but the princess manages to escape through the hands of Tiwari(Jairaj). The princess is brought up by Peter and she become Mary, a thief, when she grows up. In the meanwhile, Kishan (Rajesh Khanna), also becomes a thief. They meet and come close to each other. Finally, it is proven that Mary is the lost Rajkumari, through her locket. In the end, Kishan and Mary get married and live happily in Chandpur.