Lucas Cole, prosecutor and single parent, faces a day of life-defining choices when he is enticed to dismiss a charge of hit and run while intoxicated, by the wife of a wealthy media mogul.

Arthur Fleck works as a clown and is an aspiring stand-up comic. He has mental health issues, part of which involves uncontrollable laughter. Times are tough and, due to his issues and occupation, Arthur has an even worse time than most. Over time these issues bear down on him, shaping his actions, making him ultimately take on the persona he is more known as...Joker.

Arthur is a rich, alcoholic playboy with no regards to his working life. After another drunken run-in with the law, his aloof mother has had enough and forces him to marry Susan, a proper business woman, or else he will lose his inheritance. Just as he's engaged to Susan, he meets Naomi a free-spirited girl who Arthur thinks is perfect for him. Any attempts at holding down a job are fruitless, so Arthur has to decide, what is more important: love, or his mother's money.