Phoenix’s character, Arthur Fleck, is told he will no longer be able to see his psychiatrist and then has his stand-up comedy show mocked by a late night host portrayed by Robert De Niro.
“All I have are negative thoughts,” Fleck says to the psychiatrist.
Fleck reaches a breaking point and begins to don clown makeup and a purple suit. As The Joker, Fleck brings mayhem to Gotham City as others begin to dress up like clowns and clash with police.
The trailer ends with Fleck being invited onto the late night show where he wants to be introduced as The Joker.
Joker, from director Todd Phillips, is set to arrive in theaters on Oct. 4. Zazie Beetz, Marc Maron, Bill Camp, Frances Conroy, Brett Cullen, Glenn Fleshler, Douglas Hodge, Josh Pais and Shea Whigham also star.
Phillips confirmed in June that the film will be rated R.
