Based on what has been revealed in the trailers thus far, the production photos and videos from Cleveland and the limited marketing pieces currently out there I thought I’d take a stab at trying to determine the plot of the film and a basic flow of how it will proceed. Please note that this is an educated guess and I welcome any feedback or criticism you folks are willing to offer.
I think one of the opening scenes of the film will be Cap in the boxing gym. Fury will discuss the change in the times establishing Cap as a “man out of time” and will establish the Tesseract and the plot revolving around SHIELD’s attempts to reignite it as a power source. It will be explained that some of the world’s best scientists are being assembled to work on the project i.e. Eric Selvig and Bruce Banner. We will learn that SHIELD is currently tracking down the latter in an attempt to recruit him.
We will see Black Widow undergoing some type of “black-ops” type mission with her dressed as a kind of hooker or “black widow” gaining the attention of men and beating the necessary info out of them (as seen in the first trailer). Perhaps this info revolves around the potential shape-shifting beings/invaders who appear later in the film or around humans working for Loki/another villain to help locate the cube.
The film will cut to Black Widow finding and discussing with Bruce the need to join the Avengers/SHIELD. He will accept and leave the “man-on-the-run” aspect of his life behind for a time and join the team.
We will be introduced to Hawkeye while he and Fury are at this NASA/SHIELD dark matter research facility. It’s here that I believe Loki will make his appearance and physically transport himself to Midgard using the Gem Stone attached to his staff. I think this is the scene in the trailer were the helicopter is landing. After a brief battle with SHIELD he will escape the NASA facility via the truck he is seen riding on the back of in the first trailer. Coulson will ask Fury, “What do we do?” Fury will respond, “We get ready.”
Meanwhile, Loki will initiate his attack on the Germany city as seen in the production videos and pictures. At this point I’m not sure what his motive for doing so will be or why this German city is relevant. I think there is a chance this “theater” is potentially where the cube is being housed or hidden. Not sure about that. Cap will be sent in to fight Loki and at some point he is defeated and taken into SHIELD custody.
At this point let me say this...I’m not sure how Thor ends up back on Midgard. There has been some intense speculation as to how that happens. I have two theories on that and will describe both.
My first theory is that once Fury realizes its Loki they’re dealing with he tasks Selvig and others to figure out a way to transport Thor to earth perhaps using the same platform that transported Loki or perhaps he uses the device that transports them back to Asgard at the end of the film?? Not sure on this.
With Loki in custody Fury will assemble Cap, Iron Man, Widow and Hawkeye aboard the Helicarrier for added security. This will include the scene where Cap says the whole, “Big man in a suit of armor…” However, it will have been Loki’s plan all along to be captured thus giving him a chance to obtain the cube which is now aboard the Helicarrier. And explosion goes off inside the meeting room the Avengers are in (as seen in the trailer). Loki will escape unleashing Banner as the Hulk in the process to create a diversion. Tony will suit up and we will see the Avenger’s standing aboard the Helicarrier with a portion of it’s haul damaged from the Hulk’s escape.
Hulk’s escape will escalate into the fight in the woods as seen in the first trailer. (2nd Theory) Loki will use the Cube to transport Thor from Asgard to Earth at this point in the film. Thor, unfamiliar with is surrounds will see Hulk, Cap and rest of the Avengers as a potential threat and a battle will ensue. Once the big four have effectively kicked the crap out of each other it will be determined by either Fury or Coulson’s intervention that they are all essentially fighting for the same side.
Regrouped aboard the Helicarrier Fury will lay out the premise for the Avenger’s Initiative and will describe how SHIELD has been monitoring many things for the past several years. It will be revealed that there is the potential for “other worldly” beings attempting to steal the Cube due to its great power…thus the need for a special group of people to protect the world from threats that SHIELD themselves can’t handle. The Avengers are born! Fury will discuss with Thor the need to do whatever is necessary to defeat Loki. (“What are you prepared to do?”)
I think the meeting between Loki and Tony takes place after this hence the reference Tony makes in the new trailer to the team being called “The Avenger…Earth’s Mightiest Heroes type stuff”. I think this scene will turn out to be all an illusion created by Loki which will explain Tony being thrown out the window at the end. Perhaps Loki knows Tony’s personality and tries to win him over with aspirations of role in his newly conquered earth.
Ultimately the third act will begin with the invasion of loki's army and the epic battle on the streets of NYC. Loki in possession of the cube will transport this mysterious army to earth to begin subjugating humanity. There will be an epic montage of each respective Avenger battling the invaders.
At some point Hawkeye, Widow and Cap will crash one of the Quinjets and proceed on foot to the meeting point with all the Avenger circled back-to-back. Cap and Hawkeye will end up in Loki’s presence. I think at this point Loki will reveal that he is secretly working for Thanos in order to obtain the Tesseract which he will exchange for control of Earth. Cap will receive the majority of his battle scars in this scene and will ultimately be thrown or jump out of a window landing on a park car. Thor will come to his aid and the two fight side-by-side until the scene where the two stand facing something in the air. I think this is potentially where Thanos arrives or…
…according to speculation and the cancelled video game that was in development Hulk at some point ends up inside the alien “mother-ship” or Leviathan as it’s be referred to. He will greatly damage this ship resulting in the army either fleeing or it crash landing.
I think there is a good chance Thanos could also appear at some point towards the end of the fight and either Loki will turn on him once he sees the error of his ways or Thanos will abandon Loki reclaiming his Infinity Gem in the process.
Our heroes will undoubtedly save the day in dashing fashion.
I believe the film will end with them deciding to go there separate ways. Thor will take Loki back to Asgard, via the device created by Eric Selvig seen in the set photos, to receive Odin's punishment. Stark and Banner will drive off into the sunset in a nice new Acura NSX. Steve will begin trying to pickup to pieces of his past life, figuring out what happened to Peggy and such. Clint and Natasha will go back to SHIELD.
So there you have it. Like I said it’s just a general guideline for how I believe the movie will go. Feel free to discuss as usual below.