A taxi driver in New York, Travis Bickle—a man who seems to live on pornography—is someone who struggles to connect with others and feels insignificant. The narrative follows his slide into instability because he’s unable to form relationships and believes himself to be unimportant. He's essentially unnoticed; he doesn't matter. Walton chooses to separate himself from the people around him rather than try to fit in. Then, deciding he wants to become someone of consequence, he plans to kill a politician. This person who considers themself better than everyone else has clearly lost it, and that’s bound to result in violence—a great deal of it will be directed at himself.

Source on TMDB