A new, very compelling theory in regards to the plot of Avengers 4 has surfaced online. Ever since Infinity War concluded, a ton of various theories have surfaced online in an attempt to try and figure out what the remaining heroes can possibly do to undo Thanos' incredibly deadly finger snap. This theory not only gives an interesting answer to the how, but it changes much of what we think we know about the Marvel Cinematic universe up to this point.

Warning: possible spoilers ahead for Avengers 4. Even though this is just a theory, if it even partially turns out to be correct, it would be a huge spoiler for the movie. So anyone who wants to go in clean may want to avoid this. That having been said, the theory showed up on Reddit and was cooked up by user ch671. Basically, it assumes that the all-but-confirmed prevailing theory that the movie will use time travel is correct, while also assuming that Tony Stark will create his own version of the Infinity Gauntlet in order to try and balance the universe.

The idea is that our heroes will traverse time to collect the Infinity Stones themselves. This theory states that they'll start at the Battle of New York from the ending of 2012's Marvel's The Avengers, since both the Space Stone and Mind Stone were in play. As MCU fans will recall, Tony Stark, at the end of the battle, takes a nuke through a wormhole in space and, at the very last second, falls back to Earth, narrowly escaping death. Or does he? Here's what ch671 has to say about that.

"Tony Stark actually died when he went through the portal and the future Tony Stark replaced him and made it back through time at that exact moment! Remember this was the only chance Tony from the future had to switch places with the Tony from the past. The portal closed on him as he was about to fall through so he was actually left stranded in space. Or he was somewhere in between. Could those two seconds of yellow lightning have anything to do with the quantum realm/time travel. We know from Ant Man and the Wasp that Quantum realm is yellowish in color, exactly like those two seconds."

This would be a mind-blowing reveal and would make the ending of The Avengers rather dark. It would mean the Tony Stark we think we know and love actually died at the end of the movie. It would also mean that, once the heroes sort out this Thanos business, Tony would likely have to remain dead in order to keep the timeline straight.

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As the theory mentions, this also takes into account what we learned in Ant-Man and the Wasp about the Quantum Realm. Time doesn't work the same way in that strange place and, as noted, there are color similarities between that landscape and the lightning we see at the end of The Avengers before Tony Stark plummets back to Earth. There are some big problems with this theory, but ch671 has answers.

"How can there be a Tony from the future if Tony died in the portal? This one is obvious. The original Tony was supposed to come back but Tony from the future realized it's better to switch suits and let the old Tony die. Maybe everything that happened after Avengers 1 happened because Tony Stark from future made it back. In an alternate universe where the old Tony died and the future Tony didn't make it back, things go a lot worse for Avengers without Tony. Maybe that's why he sees a vision of them dead in Avengers 2 and decides to build Ultron. Maybe Dr. Strange knows Tony from Infinity war HAS to make the trip back in time to ensure things go as they do, and that's the only one in 14 million chance that they have. Obviously this is time-paradoxical and very hypothetical but since when has something like that stopped sci-fi movies from imagining."

It's all a big head trip, as time travel can often be. For the time being, all we're left with is theories, since Marvel is keeping the plot closely guarded. Avengers 4 is set to arrive in theaters on May 3, 2019, and Kevin Feige recently promised that the trailer will arrive before the end of the year. Maybe that footage will help clue us in as to what is really going on, or if this theory has any real weight to it. To read the theory in its entirety, head on over to Reddit.