Travis Bickle (RDN) is a New York cabbie. A nice hearted guy who falls in love with Betsy(CS) a beautiful campaign girl for the presidentia l candidate Charles Palantine (LH). She ditches him after he takes him out for a movie, but as ingenuous as he is, he took her to watch a XX movie.

One day a girl sits in his cab and asks him to move. But before he could start a guy pulls her out and takes her. This thing keeps going through his mind again and again, everytime he sees the $20 bill thrown at him by the guy. One day he sees her, Iris (JF), as she accidentally comes in front of his cab and walks off. Iris is a 12 1/2 yr old prostitute and the guy was her pimp. The $20 bill keeps bothering him. Till one day he decides that there is too much scum on the NY streets and he has to do something to clean it up.

He starts preparing. Buys weapons, starts exercising to get into shape. He murders a mugger robbing a shop cashier. Then he sets out to save her. Will he succeed?