Joaquin Phoenix and Lady Gaga bash skulls and belt songs in wickedly fun Joker: Folie à Deux trailer

The musical — and bloody — opus of Joaquin Phoenix and Lady Gaga crescendoes to a symphony of violence in the new, wickedly fun Joker: Folie à Deux trailer.

With only two months to go until the film hits theaters, the new full-length trailer takes us deeper into the shared psychosis of Phoenix's Joker and Gaga's Harley Quinn, a pair of intertwined lovers who team up to exact revenge on a city that, they feel, ostracized them from society.

The new trailer opens with Phoenix as Arthur Fleck, as he's being transported in the back of a car to Gotham City's infamous Arkham Asylum. He begins to cackle as a voice on the radio dubs him "some kind of martyr," and he is quickly proved wrong by finding a partner in crime (literally). Arthur eventually strikes up a romantic bond with Harleen Quinzel (Gaga), a fellow patient who, judging by her penchant for the institution's piano, harbors musical talents that enchant her new love interest. She even gently sings lyrics from "Get Happy" (the classic tune from 1950's Summer Stock) as a means to inspire her man before they unleash their reign of terror on the urban cityscape.

“When I first saw Joker, when I saw you, for once in my life, I didn’t feel so alone anymore,” Harley says in the preview before shattering a store window and stealing a television set. Things get worse as the preview progresses, with Joker and Harley feeding off of each other's madness, and Arthur dialing up the violence in his ongoing trial for the crimes he committed in the first film. The clip eventually shows Joker holding a mallet and using it to smash the judge's head.

Tuesday's new trailer for director Todd Phillips' Joker sequel arrived just under four months after the studio unveiled the first teaser for the project in April, which re-introduced the Academy Award-winning Phoenix as the beloved character he first played in 2019's Joker, as well as shepherding Gaga's take on Harley Quinn into the DC arena.

In that clip — soundtracked by "What the World Needs Now Is Love" — the pair wreak havoc on Gotham City amid an aesthetic that recalls movie musicals of the past, from The Umbrellas of Cherbourg to touches of La La Land. Also in the preview, glistening stage lights spell out the title of a (potentially imagined) variety show called Joker & Harley, where many of the duo's "dream ballet"-style performances might culminate. The footage ends with a particularly haunting shot of Harley drawing the Joker's signature bright red lips over a glass panel separating prisoners from their visitors.

Phillips previously elaborated on the new movie's tone at CinemaCon earlier this year, telling attendees that "it's a film where music is an essential element" that "doesn't veer too far from the first film" in that regard.

"Arthur [Fleck]'s weird and aloof and all these things, but he has music in him. He has a grace to him. That informed a lot of the dancing in the first film," he continued. "It didn't feel like that big of a step here. It's different, but I think it'll make sense when you see it."

Sign up for Entertainment Weekly's free daily newsletter to get breaking TV news, exclusive first looks, recaps, reviews, interviews with your favorite stars, and more.

Ahead of the teaser's debut, Warner Bros. dropped an official preview of Oscar winner Gaga's voice as Harley, with her vocal intonation contrasting other actresses' interpretations of the character in the past. The villainess is typically shown to have a thick Brooklyn accent — most notably, perhaps, by Batman: The Animated Series voice actress Arleen Sorkin, who originated the character for her official DC debut in the TV show as Joker's love interest.

Margot Robbie continued the trend with her foray into the DC Extended Universe's live-action projects, such as the Suicide Squad films and Birds of Prey, while Kaley Cuoco also voiced Harley with an accent in the Max animated series Harley Quinn.

Upon its release in 2019, the first Joker film received widespread commercial and critical success, earning over $1 billion at the global box office and scoring 11 Oscar nominations, including Best Picture. Phoenix won his first Academy Award for playing the titular role, and his follow-up performance (as well as Gaga's) has already landed among early awards contender lists.

Joker: Folie à Deux — also featuring the return of actress Zazie Beetz, cinematographer Lawrence Sher, composer Hildur Guðnadóttir, and producer Bradley Cooper — releases Oct. 4 in theaters. Watch the new trailer above.