Arun Verma, a professor of Psychology comes across a student, Pooja, who has not spoken to her father in since her childhood and has become almost mute and socially introvert. Her father Velji Bhai is a dreaded underworld kingpin and loves his daughter a lot. On Velji Bhai's request Professor Verma agrees to counsel Pooja at her home and soon comes to realize that Velji Bhai's life style and profession is the major cause of Pooja's problems. Professor takes Pooja out of town for a class excursion. During the excursion Pooja falls in love with a fellow classmate, Atul. She retuns home as a radically strong, confident and self assured person ready to fight her won battles. Velji is furious at her new pronounce rebellion and gets violent at the professor. The final showdown brings a dramatic metamorphosis in the life of daughter, father and the professor. Sir is an extra ordinary spellbinding tale of love, hate, and ultimate nobility of mankind.