Zombie Captain America in 'What If...?' teaser

Anaheim: Zombie Captain America fighting with Bucky Barnes, Peggy Carter picking the shield to become Captain America, and Wakanda king T'Challa transporting to a galaxy far away to become Star Lord -- no these are not plots of upcoming Marvel films, but some of the spins to be presented in the animated series "What If...?".

Time, space and reality is a prism of endless possibility," Jeffrey Wright said as a narrator in the teaser video of "What If". And that's what the show promises.

Marvel chief Kevin Feige said the series will tie into the 23 films of the Marvel Cinematic Universe in a way that they will highlight "one little difference" in each episode that changes the outcomes and lives of the beloved superheroes dramatically and drastically. It will explore how one tweak could have changed the story as well as the outcome.

The series, which will stream on Disney+, will feature voices of almost all the actors, who have worked in the films from the studio. However, it's not yet confirmed if Robert Downey Jr and Chris Evans will embrace their superhero avatar once again to give their voice to the characters.

The calming voice of Wright as The Watcher opened the teaser video at the D23 Expo.

"Time, Space, Reality, it's more than a linear path. It's a prism of endless possibility. Where a single choice can branch into infinite possibilities, creating alternate worlds from the one you know; a reflection of what could've been. I am the Watcher. I am your guide through these vast new realities. Follow me and dare to face the unknown. And ponder the question, what if...?" He said.

What followed? A tantalising tease making the wait more difficult.

There was Black Panther as Star-Lord, a glimpse into a world where Bucky didn't fall off that train and battles a zombie Captain America. The most exciting part is Hayley Atwell's Peggy Carter becoming Captain America.

"It feels like the gift that keeps on giving. The fans, they love Peggy, they've brought her back," Atwell said on stage.

The actors who will be lending their voices include names like Michael B. Jordan, Sebastian Stan, Josh Brolin, Mark Ruffalo, Tom Hiddleston, Samuel L. Jackson, Chris Hemsworth,Karen Gillan and Jeremy Renner among others.

"What If…?" will premiere on Disney+ in 2021.