Lady Gaga is to play Harley Quinn in the sequel to the multi-award-winning Joker, which is due to see Joaquin Phoenix return to his lead role.

According to the Hollywood Reporter, Gaga is in line to take the role of Quinn, the former Arkham Asylum psychiatrist who has regularly appeared in Batman-related narratives as the Joker’s sidekick and love interest. Margot Robbie played the character in a high-profile outing in the 2016 film Suicide Squad, as well as its 2021 sequel The Suicide Squad. Robbie’s version of the character was also the central figure in the 2020 superhero film Birds of Prey.

No details of the film’s plot have been revealed, but the Reporter says that Joker 2’s Quinn will “exist in a different DC universe than … Robbie’s Harley Quinn” – presumably reflecting the first Joker’s distant relationship with previous iterations of the character. Director and co-writer Todd Phillips posted a script cover page on social media on Wednesday suggesting the film’s subtitle is “Folie à Deux”, a reference to a psychiatric syndrome in which a delusional state is shared by two people, which could well refer to Quinn’s place in the film’s narrative.

The Reporter also states that Joker 2 will be “a musical”, though offers no further details.

In the same social media post Phillips also revealed a photograph of Phoenix reading the script, although reports say that Phoenix has not yet committed to the project. The Reporter says its sources claim that “Warners has yet to close a deal with the actor, with the two sides deep into it”, but it is inconceivable the project will move ahead without his participation.

Lady Gaga’s move into film acting has proved exceptionally successful so far, having received an Oscar nomination for best actress for A Star Is Born, and Bafta and Golden Globe nominations for best actress for House of Gucci.