This is going to be stupid isn't it. Ok some back story Steve Rogers is Captain America. Then he got his super soldier serum drained out of him and aged to Old man Steve. Over time he gets that back and takes up the role of Cap again. Then things get weird see turns out Cap was never a good guy, He not the people's champion he never was he was always Hydra's Champion. See we are led to believe that Red Skull rewrote Caps mind and backstory so he was a agent of hydra the whole time.
The big reveal at the end of issue 0 is..... The Allies actually LOST WW2 , and used the Cosmic Cube to rewrite history and turn Steve Rogers into Captain America
So now with his secret out, we have Captain, The guardians of the Galaxy, Nova and others trapped off world along with the Defenders, the Uncanny Avengers, and tons of other superheroes who call the city home trapped inside the Dark Dimension.
Dont say its not worth it, when you can sleep with no fear, that kind of time is worth any thing.- FFX
It wasn't. It was added for the movie. I was under the mistaken impression the movie and the book were the same thing continuity-wise and that the movie just expanded on things here and there while omitting other things for running time.