12 Interesting Age Of Ultron Theories Based On The Trailer

4. Captain America Seeks Out The Time Gem

There is a scene in the trailer in which Captain America opens some doors in a building that lead to some stairs which head underground. The scene happens after a shot of a large building in some mountains - which we believe to be the same building - and it's fairly clear that Captain America has travelled a long way in search of something. We think that "something" is the Time Gem (or the Marvel Cinematic Universe equivalent) - and that Nick Fury had suggested that he go find it in order to time travel. Not only will it provide a method to defeat Ultron, it will also add another Infinity Stone in to the mix in time for the third Avengers movie, when Thanos will be wielding the completed Infinity Gauntlet.