Watch: Joaquin Phoenix, Lady Gaga connect, cause chaos in 'Joker: Folie a Deux'

July 23 (UPI) -- Warner Bros. is teasing the new film Joker: Folie à Deux.

The studio shared a first full-length trailer for the movie Tuesday featuring Joaquin Phoenix and Lady Gaga.

Joker: Folie à Deux is a sequel to the 2019 film Joker. Both films are inspired by DC Comics characters and are co-written and directed by Todd Phillips.

Phoenix reprises his role as Arthur Fleck, aka Joker, while Gaga joins the cast as Harleen Quinzel, aka Harley Quinn.

"Joker: Folie à Deux finds Arthur Fleck institutionalized at Arkham awaiting trial for his crimes as Joker. While struggling with his dual identity, Arthur not only stumbles upon true love, but also finds the music that's always been inside him," an official synopsis reads.

The trailer shows Joker (Phoenix) and Harley Quinn (Gaga) connect at Arkham Asylum and cause chaos in Gotham City.

Brendan Gleeson, Catherine Keener and Zazie Beetz also star.

Warner Bros. shared a teaser trailer for the movie in April.

Joker: Folie à Deux opens in theaters Oct. 4.

The film marks Gaga's second starring movie role after A Star is Born (2018). The singer and actress announced last week that she is recording new music.