What's 'Joker' even really about?
Attempting to bring a dose of gritty reality to the genre, Joker is relatively straightforward in demonstrating how Arthur goes from sad party clown to leader of a reign of terror in 1970s Gotham. While Phillips has essentially attempted to recreate Taxi Driver's New York, every so often you are thrust back into the realization that, no, it's actually Gotham, home of Arkham Asylum.
We meet Arthur, a wannabe stand-up comedian, after he has been institutionalized for unknown reasons. He has a condition that makes him laugh uncontrollably at inopportune moments, and is treated as a human punching bag by nearly everyone, save for his dotty mother (Frances Conroy). As Arthur suffers injustice after injustice, his anger swells, abetted by the fact that he is denied access to his mental health medications. He's taunted by three douchebag Wayne (as in Bruce) employees on the subway, snaps, kills them, and finds a confidence in that power. From there, he grows further disillusioned, adopts his "nothing matters" ethos, and finds a grim giddiness. (That dance sequence you've seen popping up in all the marketing is an indicator of this, but there is an issue within that too: It uses the music of convicted pedophile Gary Glitter.)