Nagina is a fantasy romantic drama. The movie revolves around a shape-shifting cobra named Rajni (Sridevi), who sets out to exact vengeance from the evil saint named Bhairon (Amrish Puri), who killed her spouse. She takes up the shape of a human and marries a civilian named Rajiv. Rajiv is madly in love with Rajni, unaware of the fact that she is a shape-shifting cobra, with the intentions of her own, and she only married him to take revenge from Bhairon. What will happen when Rajiv learns the truth?