Quick recap
Gotham, 1981. Arthur Fleck works as a clown, dreams of doing stand-up and has a condition that makes him laugh uncontrollably. He lives with his mother, Penny. After a beating on the street he gets a revolver and, on the subway, kills three Wayne Investments employees who attack him. The killings spark clown-mask protests. Arthur comes to believe he's Thomas Wayne's son, until he learns his mother lied and let him be abused as a child. He kills Penny. Talk show host Murray Franklin mocks a clip of him and invites him on. Live on air, Arthur asks to be introduced as Joker and kills Murray. In the riots that follow, a rioter kills Thomas and Martha Wayne in front of young Bruce. At the end, Arthur is in Arkham.

