Mast Kalandar is an action thriller drama. It follows the story of a rich tycoon Rai Bahadur Pratap Singh (Shammi Kapoor), who lives a wealthy lifestyle with his son. He wants his son to get married to a girl from a wealthy family, however, his son falls in love with a poor girl and elopes to marry her. Years later, Pratap learns that his son is dead, but his daughter-in-law and grandson are alive. Will Pratap be able to find his estranged grandson and daughter-in-law?