Lady Gaga's Harley Quinn joins Joaquin Phoenix's Joker in the new film, which finds Arthur Fleck institutionalized at Arkham awaiting trial for his crimes as Joker. Per Warner Bros., "While struggling with his dual identity, Arthur not only stumbles upon true love, but also finds the music that's always been inside him." The movie, which will feature musical numbers, opens October 4, 2024.
