Joss Whedon says that they are crafting their own version of the Age of Ultron story.
The director has revealed that Ultron will be the major villain in Avengers 2, but it is not story that has been directly inspired by any of the comic books.
Marvel.com did a live interview with Whedon at Comic Con where the director discussed what we can expect from the Avengers sequel.
"A lot of people - because we called it Age of Ultron and there was a book, Age of Ultron just recently - assumed that was the storyline we are doing, which is not the case. We’re doing our own version of the origin story of Ultron.
"The other thing is, in the origin story, there was Hank Pym. So a lot of people assumed that he was going to be in the mix, but he’s not. Because we’re basically taking the things from the comics for the movies that we need and can use.
"A lot of stuff has to fall by the wayside. Ultron was their chief villain. He’s been the Avengers villain for so long. I was amazed anybody was surprised that it was going to be him in the movie.
"We are crafting our own version of it where his origin comes more directly from the Avengers we already know about."
Whedon is currently working on the script for the film and said that filming will begin at the end of February/beginning of March next year.
Robert Downey Jr, Chris Evans, Chris Hemsworth, Scarlett Johansson, Mark Ruffalo and Jeremy Renner are all expected to reprise the roles of Iron Man, Captain America, Thor, Black Widow, Hulk and Hawkeye.
Avengers: Age of Ultron is set for a May 2015 release.
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