Word around the block is that the work on the sequel to Todd Phillips' Joker, Joker: Folie a Deux, will be starting 
before the end of 2022. In a recent interview, cinematographer Lawrence Sher revealed that he will be headed to work on the Joker sequel as filming is expected to begin in five or six weeks. Sher also said that the film will be shot largely on sound stages in Los Angeles as well as on location in New York. 

The film will star Joaquin Phoenix reprising his role as Arthur Fleck / Joker with Lady Gaga joining the cast as his beloved Harley Quinn. "She's going to be a really cool fit for this movie and will create a similar kind of magic that Joaquin brought by himself," Sher said. "The combination of the two will be exactly what we hope, which is exciting, and we'll find magic every day on set. Hopefully we'll also have a bit of madness in there. We like when there is a little bit of chaos."

Back in August it was revealed that the Joker sequel will be released on October 4, 2024 — exactly five years after the original film. Talk of a sequel has been ever present for the past three years and Phillips made things official when he confirmed the title for the Joker sequel. The Folie a Deux subtitle refers to the medical condition where two or more people start sharing delusions, which initially led many to believe Harley Quinn would be involved.

Lady Gaga will be stepping into the role of Harley Quinn, who was previously played by Margot Robbie in Suicide Squad, Birds of Prey, and The Suicide Squad. Since Joker is not set in the same universe as the DCEU (Detective Comics Extended Universe), Margot Robbie could still return as the character in her respective universe.