Sadma is a romantic drama following the story of a young woman named Nehalata Malhotra (Sridevi). One day, while returning from the party, Nehalata meets with an accident and suffers severe injuries. She regresses to childhood, and gets kidnapped by an owner of the brothel. In the brothel, she is discovered by Somu (Kamal Haasan), who empathises with Nehalata, now renamed as Reshmi, and helps her run away from the brothel and brings her to his house in Ooty. Soon after, Nehalata’s parents track her down are ready to take her away. However, it is to be found, whether Somu will be able to face the separation from Nehalata or not?