Put on a happy face.
In Gotham City there is a huge social divide between the rich and the poor. Advocating the needs of the rich is Thomas Wayne (Bruce Wayne’s father), who is running for mayor. On the other side of the gap, Arthur Fleck is fighting for his existence. A medical disorder forces him to laugh at random times, which makes him a constant target for mockery and bullying.
Arthur dreams of becoming a stand-up comedian, but for now is forced to work as a clown, advertising restaurants and entertaining little children. During a brawl on the subway train, some rich kids feel provoked by his inappropriate laughter and beat him up. In full clown costume, Arthur has to resort to extrem measures to defend his bare life.
Details of the train incident are soon known throughout Gotham, but Arthur’s mask hides his identity. Although this was far from his intention, it is widely seen as an act of “The Poor” rebelling against “The Rich” – and the clown’s mask becomes a symbol of the revolution.
When Arthur finally gathers the courage to go on stage as a comedian, instead of applause he recieves ridicule from the audience, and also from his childhood idol Murray Franklin, who hosts a late night show and makes fun of a video of Arthur’s performance. But the video goes viral and Arthur is actually being invited to Murray’s show, where he is intruduced as “Joker” and gets a chance for a statement …