SPOILER ALERT: This article contains major spoilers for the ending of “Captain America: Brave New World,” now playing in theaters.

Captain America has saved the world once again but he still has one more mission ahead of time: reassembling the Avengers.

Anthony Mackie‘s Sam Wilson took over from Chris Evans’ Steve Rogers and led his first MCU movie with “Captain America: Brave New World,” defeating the powerful Red Hulk (Harrison Ford). However, the post-credits scene featuring gamma-irradiated genius Samuel Sterns (Tim Blake Nelson), aka the Hulk villain Leader, teased that there are more multiverse threats in the MCU.

By the end of the movie, Cap learns that Sterns is the one responsible for providing Ford’s President Thaddeus “Thunderbolt” Ross with heart pills that secretly contained gamma radiation, thus turning him into the Red Hulk when he loses his temper. Sterns’ nefarious plot was revenge for Ross playing a part in his transformation into a jolly green mad scientist (with a hideously enlarged brain).

After a battle that destroys the White House, Cap defeats Red Hulk/Ross and locks up Sterns in prison. Ross also turns himself over and decides to serve jail time for his Red Hulk rampage. That does beg the question, who becomes the U.S. president while Ross is in jail? We don’t get an answer to that, but we do know, via a brief cameo, that Sebastian Stan’s Bucky Barnes, aka the Winter Soldier, has a rising career in politics. He’s revealed to be an incoming U.S. congressman. We’ll see Bucky next in this summer’s “Thunderbolts” movie, but it appears he’s a member of the new anti-hero/villain team and not a politician in the film.

In the post-credits scene, Cap visits Sterns, who’s locked up in the Raft. In an ominous speech, Sterns says he has calculated the probabilities and that there are other worlds out there in the universe that Earth’s heroes will have to protect the planet from. This officially introduces Captain America to the multiverse, but MCU fans have already witnessed it come to life in “Doctor Strange in the Multiverse of Madness,” “Spider-Man: No Way Home,” “What If…?” and soon in “Fantastic Four: First Steps.”

The scene seems like it’ll tee up the next “Avengers” movies, “Doomsday” and “Secret Wars,” which are sure to bring together lots of characters from across the multiverse. We know that Robert Downey Jr. will return to the MCU in those movies — but as supervillain Dr. Doom and not Iron Man in a reality-bending twist. This summer’s “Fantastic Four” will also introduce an alternate world that counts Mr. Fantastic, the Invisible Woman, the Human Torch and the Thing as its main superheroes. If they cross over into Cap’s world, will he get along with the new team to face Dr. Doom? Hopefully Cap can reunite Earth’s Mightiest Heroes in time to face this ultimate threat to the multiverse.