The first 'Joker 2' trailer looks as chilling and twisted as the first movie

• The first trailer for "Joker: Folie à Deux" screened at CinemaCon on Tuesday night.
• Director Todd Phillips said, "Lady Gaga is magic," when asked why she was cast to play Harley Quinn.

During the Warner Bros. presentation on Tuesday at CinemaCon, the annual movie-theater convention in Las Vegas, the trailer for "Joker: Folie à Deux," the sequel to the studio's 2019 hit movie "Joker," was unveiled for the first time and received thunderous applause.

The trailer featured Joaquin Phoenix returning to play the role of Arthur Fleck, aka Joker, along with the addition of Lady Gaga to the franchise, as she plays Joker's love interest, Harley Quinn.

"Joaquin and I always talked about doing a sequel while making the first movie," director Todd Phillips told the CinemaCon audience. "But we didn't want to jinx it. But then the pandemic hit, and we talked more and decided to do it."

"Lady Gaga is magic, and when we wrote the script, we kept thinking about her," Phillips added about adding Lady Gaga to the cast.

Phillips also added about the reports of the movie having a musical vibe.

"We never talked about it as a musical, Phillips said. "Music is an essential element, just like the first movie. It didn't feel like a big step. It will all make sense when you see it."

"Joker: Folie à Deux" opens in theaters on October 4.

2019's "Joker" was a huge success, earning over $1 billion at the worldwide box office. It is also the highest-grossing R-rated movie ever at the worldwide box office. The movie also received 11 Oscar nominations with wins for Best Actor (Phoenix) and Best Original Score.