'Joker: Folie à Deux' director reveals more about film's Lady Gaga/Joaquin Phoenix musical performances

The upcoming sequel Joker: Folie à Deux has been described as a musical that will feature Lady Gaga and Joaquin Phoenix 's characters singing, but now we have more details on how that plays out.

Variety reports that the movie is set two years after the first movie, and finds Phoenix's Arthur Fleck aka Joker in a psych ward, facing the death penalty. After he meets another patient, Gaga's Harleen Quinzel, he stops taking his meds and enters a fantasy world inspired by old-fashioned musicals. Together, they sing classic songs like "For Once In My Life," "That's Life" and "Get Happy."

Speaking to Variety , Gaga says director Todd Phillips "took a very big swing with this whole concept," adding, "There's music, there's dance, it's a drama, it's also a courtroom drama, it's a comedy, it's happy, it's sad."

Still, Phillips says he's not sure the film is a musical. "Most of the music in the movie is really just dialogue,” he says. “It’s just Arthur not having the words to say what he wants to say, so he sings them instead.”

Plus, he notes that the musical performances take place within Harleen and Arthur's imagination, not in the "real world." Gaga and Phoenix sang all the songs live while filming, accompanied by an off-camera piano player.

“We asked ourselves, what would need to be true for two people to just break into song in the middle of a conversation?” Gaga says. “Where does the music come from when no one can hear it but the characters?"

Phillips also says Gaga's portrayal of Harley Quinn is different than how the character's previously been depicted, explaining, "The high voice, that accent, the gum-chewing and all that sort of sassy stuff that’s in the comics, we stripped that away."