Disney unveiled a new trailer for “Avengers: Doomsday” at its D23 fan event on Friday. It gave audiences an extended look at Robert Downey Jr.’s turn as Doctor Doom.

The footage leans harder on Doom’s backstory than anything Marvel has shown so far. The Fantastic Four brief the rest of the Avengers on what happened to him, describing a man who lost everything he loved.

Sue Storm, the Invisible Woman, tells the assembled heroes that Doom “used to be different” and “used to be kind” before tragedy broke him. Doom answers her directly in the trailer: “All of you have lived stolen lives.” Then: “Hell answers to me. For I am Doom.”

The film brings together Marvel’s ensemble in a way the franchise has not attempted before, folding in the X-Men alongside the core Avengers roster. Captain America, absent from recent installments, returns as part of the fight against Doom.

The D23 panel ran August 14 through 16 in Anaheim, where Disney previews footage from its biggest upcoming releases. It marks Downey’s first MCU role since Iron Man died in “Avengers: Endgame” in 2019. This time, he steps into Doom’s mask instead of the Iron Man armor.

“Avengers: Doomsday” opens in theaters December 18. It sets up “Avengers: Secret Wars,” due a year later on December 17, 2027, closing out the current phase of Marvel’s interconnected story.

Anthony and Joe Russo direct the film, marking their own return to the franchise after “Avengers: Endgame.” Early reaction to the D23 footage was positive. Kotaku and Variety both called it the clearest look yet at Downey’s performance in the role.

Marvel has kept plot details tightly guarded ahead of release. But the D23 trailer is the studio’s clearest signal yet of how personal Doom’s war with the Avengers will get. Fans will find out in December whether the buildup matches the payoff.