Taxi Driver (1976)

Travis Bickle is an ex-Marine and Vietnam War veteran living in New York City. As he suffers from insomnia, he spends his time working as a taxi driver at night, watching porn movies at seedy cinemas during the day, or thinking about how the world, New York in particular, has deteriorated into a cesspool. He's a loner who has strong opinions about what is right and wrong with mankind. For him, the one bright spot in humanity is Betsy, a worker on the presidential nomination campaign of Senator Charles Palantine. After an incident, he believes he has to do whatever he needs to make the world a better place.