"Listen, you fuckers, you screwheads. Here is a man who would not take it anymore. A man who stood up against the scum, the cunts, the dogs, the filth, the shit. Here is a man who stood up."
Bickle is a former Marine who served in Vietnam. He is socially inept, has no apparent friends, and is suffering from insomnia, so he takes a job as a graveyard shift taxi driver to occupy his time. As he works late at night in dangerous neighborhoods, his customers tend to include pimps, drug addicts, and thieves. He is visibly disgusted by them, and begins fantasizing about "cleansing" such "filth" from the streets.
Bickle becomes smitten with a woman, Betsy (Cybill Shepherd), who works in the local campaign office of a presidential candidate, a Senator Palantine. He often watches Betsy from his cab, and finally enters the office with the pretense of wanting to support the would-be candidate, and asks her out. They meet for coffee, and Betsy finds him odd but intriguing, and agrees to see him again. This time he takes her to the porno movie theater he frequents, apparently seeing nothing unusual in the choice. She is appalled and refuses to see him again.
After this, Bickle becomes increasingly paranoid and starts acting out his vigilante fantasies. He buys several guns and takes to carrying them, and knives secreted about his person — taped to his limbs, for example or in hidden spring-loaded holsters. He famously practices a menacing, tough guy swagger in the mirror — You talkin' to me? — to use on whoever angers him. Eventually he shaves his head into a mohawk, and in dark glasses and a baggy military coat, attends one of Palantine's speeches, apparently intent on shooting him. He draws the attention of Secret Service agents and flees, so it is never clear whether he would have done so.
He also becomes obsessed with "saving" Iris (Jodie Foster), a 12-year-old prostitute he has seen on his route. He pays her pimp, Sport (Harvey Keitel), for her time, but refuses to have sex with her, trying instead to persuade her to leave prostitution and return home to her parents. Iris rebuffs him, only increasing his anger and resolve to take her away from a dangerous life. Although he is wounded, he shoots and kills Sport, and continues through a hotel in which Iris is servicing a client, killing the client and a bouncer with a wounded arm.
