In the eponymous role, Nargis (Meena Kumari), finds love and dreams of marrying the man she loves, Shahabuddin (Ashok Kumar). However, the patriarch of Shahabuddin's family, Hakim Saab (D.K. Sapru) rejects this alliance, as he finds it unacceptable to welcome a tawaif in his respected family. Dejected, Nargis flees to a nearby cemetery and lives there, ultimately giving birth to a daughter before passing away. On her deathbed, she writes Shahabuddin a letter asking him to come for his newborn daughter. Nargis' sister, Nawabjaan (Veena), a brothel madam, finds the girl first and brings her back to the kotha. When Nargis' belongings are sold several years later, a book lover finds the letter in her book and posts it. Shahabuddin comes to collect his now adult daughter, Sahibjaan (also played by Meena Kumari). But Nawabjaan takes her niece and flees by train to another town. While traveling by train, a dashing young man enters Sahibjaan's compartment by happenstance. He is struck by her beauty and leaves her a note with the famous lines: "Aapke paon dekhe, bahut haseen hain. Inhein zameen par mat utariyega... maile ho jaayenge [I saw your feet - they are very beautiful. Please don't step on the ground, as they will get dirty]. Sahibjaan falls in love with this mysterious stranger and yearns to meet him. The note gives Sahibjaan hope even as she avoids unwelcome attention from her patrons while entertaining them. One particular patron, the aggressive Nawab Zafar Ali Khan (Kamal Kapoor), wishes to own Sahibjaan and takes her to his boat for the night. The boat is attacked by elephants and Sahibjaan is carried away by the fast flowing river in a broken boat. As fate would have it, she is taken to the riverside tent of a forest ranger, Salim Ahmed Khan (Raaj Kumar). Alone with his diary, she reads how he was the same man who had earlier left her a note on her feet, and left for her to read it while traveling in the same compartment. Sahibjaan finally meets the stranger, but feigns amnesia to avoid telling him her true identity.