Mark your calendars for Oct. 4, 2024: "Joker: Folie à Deux" will be released in theaters.

The sequel to the wildly successful "Joker" film that earned actor Joaquin Phoenix an Oscar has been greenlighted.

Production will likely begin in December, according to Deadline.

The original "Joker" cast was full of heavy hitters, including Robert De Niro and Bradley Cooper.

Joaquin Phoenix, who played the title role in the "Joker," won an Academy Award for Best Actor for his work. (Getty Images)

The "Hold My Hand" singer-turned-actress, who most recently starred in "House of Gucci," had been rumored to be joining the film for some time.

And she revealed she would be joining the project in a post shared to her social media.

An error occurred while retrieving the Tweet. It might have been deleted.

Lady Gaga, most known for her music, has recently been taking her talents to film. (Getty Images)

"Folie à Deux" is a French phrase used to describe a mental disorder shared by two people, often in the same family.

There have been no plot revelations for the upcoming film.

Lady Gaga, seen here with another actor who portrayed the Joker, Jared Leto, is set to join "Joker: Folie à Deux." (Getty Images)

Lady Gaga confirms she will star in 'Joker' sequel with Joaquin Phoenix

'Hold My Hand' singer Lady Gaga is back to acting, set to star alongside Joaquin Phoenix in 'Joker: Folie à Deux'