Marvel Studios has gone public with the first official trailer for its movie Avengers: Doomsday after it was showcased at CinemaCon in Las Vegas in April.

Released on July 20, the 2min 25 sec trailer has hit more than 36 million views on YouTube in less than 24 hours.

The teaser begins with a battered sign that reads “Xavier’s School for Gifted Youngsters”.

“Something’s coming. Something we may not be able to deter,” said a voiceover, as Charles Xavier/Professor X (played by English actor Patrick Stewart) shields his eyes from what looks like an explosion outside the window.

The scene then cuts to the film’s antagonist Doctor Doom (Robert Downey Jr), who says: “Before this day is done, we shall be faced with an unthinkable decision.”

The role marked Downey Jr’s return to the Marvel Cinematic Universe since his character Iron Man died at the end of Avengers: Endgame (2019).

A shot of the Avengers Tower appears, and Thor (Chris Hemsworth) was heard saying: “I’ve fought with many warriors in my time.”

He enters a room with the Fantastic Four – Reed Richards/Mister Fantastic (Pedro Pascal), Sue Storm/Invisible Woman (Vanessa Kirby), Johnny Storm/Human Torch (Joseph Quinn) and Ben Grimm/The Thing (Ebon Moss-Bachrach), as they meet up with Sam Wilson/Captain America (Anthony Mackie), Bucky Barnes/Winter Soldier (Sebastian Stan) and Scott Lang/Ant-Man (Paul Rudd).

“They were far stronger than all of us put together,” said Thor. “And they died. They died facing enemies and threats that scared me far less than this one.”

Shuri (Letitia Wright), M’Baku (Winston Duke) and a group of Wakandans face off against Namor (Tenoch Huerta Mejía) and some Talokanil soldiers in the next scene.

There is a glimpse of Cyclops (James Marsden), with Gambit (Channing Tatum) fighting Shang-Chi (Simu Liu) in another scene.

“Everything that they sacrificed will be for nothing if we do not stand together,” Thor said in the voiceover, as Loki (Tom Hiddleston) twirls his TVA card (from the Loki TV series, 2021 to 2023). M’Baku shakes hands with The Thing as characters like Shuri, Sue Storm and Bucky look on.

“Put aside your petty squabbles,” Thor’s voiceover continues, as Yelena Belova (Florence Pugh) is involved in a duel with Mystique (Rebecca Romijn), with Mystique then shape-shifting into Yelena.

“And presume nothing except this. If you return, you will return as brothers and sisters,” Thor said, as Professor X and Magneto (Ian McKellen) clasp each other’s hands, Scott and Cassie Lang (Kathryn Newton) hug and Johnny and Sue Storm embrace.

“But mark my words, we’re going to need a miracle,” Thor says, as he clashes with Doom.

Steve Rogers (Chris Evans) makes a surprising return, saying: “Hey, pal” as Thor says: “It’s not possible.” The Norse god’s hammer Mjolnir then flies into Rogers’ hand.

The former Captain America is last seen in Avengers: Endgame, with his elderly self passing his shield to Sam Wilson.

Marvel also releases the poster for Avengers: Doomsday on social media on July 20. In the poster, Doom is standing on the stairs below a mural that shows a woman and a child embracing, with the picture hinting at a tragic backstory.

Avengers: Doomsday is directed by the Russo brothers, who also helmed Avengers: Infinity War (2018) and Avengers: Endgame. The new film will arrive in Singapore cinemas on Dec 18.