Avengers: Endgame will be the most unpredictable MCU film, star Robert Downey Jr. promises. The 22nd entry in The Infinity Saga, Avengers 4 will pick up after the devastating events of Avengers: Infinity War where Thanos successfully decimated half of life in the universe with his deadly snap. This left Earth's Mightiest Heroes at their lowest point as they deal with their first real loss after banding together in 2012's The Avengers. But while Avengers 3 focused on the Mad Titan's narrative, the Phase 3 capper will put the heroes - particularly MCU's founding members - at the forefront of the story.

Directed by Joe and Anthony Russo with the story written by Christopher Markus and Stephen McFeely, Endgame is arguably the most secretive MCU film to date. Marketing has been carefully designed so as not to reveal any detail that may give the public even an inkling of what's going down in the movie, while also remaining enticing for those who may not be knee-deep in the lore. Trailers supposedly have only used footage from the first 20 minutes of the film, with some shots altered to preserve its secrecy. Given all this, the public is having difficulties nailing what lies ahead for the Avengers, although that doesn't exactly discourage them from continuously trying.

In a newly released Endgame featurette that includes commentaries from the cast of the film, Downey guarantees that "there is no way anybody could guess what's gonna happen." Meanwhile, the rest of his co-stars (including Brie Larson) hype up the notion that Marvel Studios saved their best storytelling for the film. Fans in the thread expressed their excitement over the movie, but some of them also can't help mentioning the fact that Endgame's runtime is three hours.

It's no secret that Marvel Studios and the Russos went to great lengths to make sure that Infinity War' big ending was not spoiled for the public before it came out last year. Between handing out fake scripts and launching the #ThanosDemandsYourSilence social media campaign so as not to intentionally spread around details of the movie after its premiere, they were quite successful. With Endgame having more spoilers than Infinity War, it's understandable that they've been trying hard to keep the film's narrative tightly under wraps, and so far, they've been doing a great job.

As for the narrative of the movie itself, time travel and the Quantum Realm appear to be the two constant elements in fan theories with several pieces of evidence backing up these claims. But how they factor into the story remains a big mystery. Considering how Infinity War ended, there's no clear path for how things will be resolved in Avengers: Endgame - and especially with how dusted heroes such as Spider-Man and Black Panther are going to return. While not everyone was thrilled with a retreading of the MCU's fake death trope, the big mystery that fans are still trying to predict is how the Avengers will finally defeat Thanos and restore peace in the universe.