There are rumours that Brendan Gleeson will be joining the cast in a role yet to be revealed.
In the comic books the movie is based upon, Harley Quinn meets Joker while working as a psychiatrist at Arkham Asylum. The pair soon become romantically involved and wreak havoc on Gotham City. The first Joker film ended with Arthur Fleck inside Arkham on the brink of escaping.
The director and his original Joker film scooped up 11 Academy Award nominations as well as a Golden Lion win at the Venice Film Festival. Phoenix received the Oscar for Best Actor after his performance as the deranged villain.
Joker: Folie a Deux is set to hit cinemas in New Zealand on October 3, 2024, five years after the original film was released.