Joker 2: Lady Gaga appears in trailer for sequel (which isn't a musical)

Joaquin Phoenix reprises his Oscar-winning role as Joker, with Lady Gaga as Harley Quinn

Lady Gaga is seen bringing the music, dance and a very bad romance to the Joker film sequel in its first trailer.

The singer and actress plays a new version of Harley Quinn in Joker: Folie à Deux opposite Joaquin Phoenix, who won an Oscar for the original movie.

The pair seemingly meet and fall in love in Arkham Asylum before apparently escaping and forming a musical duo.

Director Todd Phillips said it isn't a musical, as had been rumoured, but that music is "an essential element".

Phoenix won an Oscar for best actor for his performance in 2019's Joker.

Here are seven things of note from the sequel's trailer.

1. Gaga is a new Harley

Arthur Fleck (aka Joker) and Harley Quinn's eyes appear to meet as she takes part in a singing group in Arkham Asylum, where he was left at the end of the 2019 film.

Her origin story is as a psychiatrist at the institution who is obsessed with the failed comedian and "crown prince of crime" - but here, she could be a fellow inmate. It's not quite clear which side of the bars she's on.

"It seems to confirm a massive shift in Harley Quinn's origin story," wrote IGN's Alex Stedman, "as it appears to show her as a patient in Arkham Asylum rather than as a psychiatrist".

"Long gone, it seems, are the days of Dr Harleen Quinzel."

But if she is working rather than residing there, that might help explain how she can help him escape.

"Let's get outta here," she whispers, before the pair are seen in a fantasy rooftop dance sequence.

That abruptly cuts to a gritty Gotham City street, where they continue their carefree dance as emergency vehicles rush in the direction of whatever chaos they have just caused.

2. The Joker & Harley band

"We use music to make us whole - to balance the fractures within ourselves," the title character is heard saying in voiceover.

Joker has found a partner in love and crime, but also music. In one clip, they perform as Joker & Harley on a TV show, complete with full band and backing singers.

The trailer is soundtracked by What the World Needs Now Is Love, made famous in 1965 by Jackie DeShannon.

"I like to say it's a movie where music is an essential element," Phillips told CinemaCon on Tuesday, when asked whether this is a musical.

"To me that doesn't veer too far from the first film," he said, adding that in that original film, "Arthur has music in him. He has a grace to him."

3. Nods to the steps routine

Indeed, one of the most famous scenes from the first film was where Joker danced down a flight of stone steps. In the new trailer, Harley is seen walking up those same steps.

In another snippet, she and Joker mimic his original dance as they go down what look like courthouse steps, with cheering crowds on either side.

Thankfully, there's no Gary Glitter music this time.

4. A white wedding?

At another point, Harley, wearing a white wedding dress and veil, dances down an aisle to a chapel, where Joker is waiting in a white suit, apparently accompanied by backing singers as bridesmaids.

This is, however, one of several fantasy sequences that are reminiscent of classic Hollywood movie musicals.

That led one person on X to say it looks like 2016 musical La La Land, but for "people who hear voices".

5. Steve Coogan!

The British comedian and actor pops up in the trailer as some sort of authority figure who asks Arthur/Joker: "What's changed?"

"I'll tell you what's changed - I'm not alone any more," he replies.

Coogan's appearance led some to hope for a repeat of a line by his most famous character, Alan Partridge, when he declared: "I'm Batman!" Which really would be a plot twist.

6. A fabulous final shot

After causing mass mayhem, with riots on the streets, an explosion in a packed room with TV cameras (the same studio as their performance?), and Joker and Harley running hand-in-hand out of a flaming building, the trailer ends quietly with Harley apparently visiting Arthur in prison.

Using her red lipstick, she draws a curved line on the glass between them and tells him: "I want to see the real you."

Phoenix's glum face slowly shifts and breaks into a big smile, which aligns with the now out-of-focus lipstick to suddenly become Joker's famous red face paint.

A masterful shot which we hope took several hundred attempts to perfect, rather than having the lipstick digitally added in post-production.

7. The wrong release date

The trailer actually ends with the release date - 10.04.24 - which means it's out TODAY! Hurrah!

Oh, wait. Americans write their days and months the wrong way around. So we'll actually have until 4 October.