The new Avengers movie is sure to be action packed and visually stunning, but in case you missed a Marvel blockbuster this summer (or earlier) here's what you need to know before watching Age of Ultron. Joss Whedon said in March 2012 that his envisioned sequel to The Avengers would be "more personal, more painful," and more intimate in scale. "I want to know what makes them tick, what makes them flawed, what makes them fight — and ultimately, what makes them awesome." To understand that intimacy, you're going to need to know the characters. The next Marvel movie, the Avengers sequel Age of Ultron, won't hit theaters until May 2015. And there's already a lot to learn. The most recent trailer (shown only to some people at Comic Con) is very dark and plays up the “global threat” angle, but what’s most interesting is the use of music. An eerie version of “I’ve got no strings” from the Pinocchio soundtrack plays over the footage with the lyrics: “I’ve got no strings, to hold me down” and “I had strings, but now I’m free”. While the full plot is unclear, I can give some hints. It seems that Tony Stark develops the Iron Legion (police robots that are like Iron Man) to take care of some of the crime, because the Avengers are tired. They are self commanding, but headed by an AI head called Ultron. Unfortunately for the world, Ultron decides that humanity is its own worst enemy, and deems it necessary to get rid of it by seizing control of a bunch of technology. So basically: Skynet, in a robotic humanoid body. There's also a few more hints (possible death sequences, anybody?!) But I don't want to think about that too much. As much as I am anticipating a better trailer, costume photos, and this movies full release, I don't want full spoilers! That being sad, there are quite a few things any Avengers fan should make sure they are caught up with before seeing Ultron: = Iron Man 3. This installment is more of a follow-up to The Avengers than a precursor to Age of Ultron, addressing Tony's PTSD since the battle in New York. Still, it sets up the icea of specialized, self-piloting Iron Man suits. The War Machine is rebranded as Iron Patriot. A.I.M. is introduced to the Marvel Universe for the first time, and Stark and Banner have kept in touch since the first Avengers film, as seen in the post-credits scene. = Thor: The Dark World. A few threads are established that may (really, truly may) show up in Age of Ultron. At the end, it is revealed that Loki, posing as Odin, has seized the throne of Asgard. During the credits, the Aether is revealed to be one of the Infinity Stones and is placed in the hands of the Collector. = Captain America: The Winter Soldier. This one is the most integral film for setting up Age of Ultron. S.H.I.E.L.D. is decimated after being infiltrated by Hydra, and Nick Fury is playing dead. In the post-credits scene, we find out that Baron Wolfgang von Strucker has captured Quicksilver and Scarlet Witch. Both of these developments factor into Age of Ultron substantially. = Guardians of the Galaxy. Guardians mostly focuses on shenanigans around the Infinity Stones, a plotline that likely leads to Avengers 3. There's not really anything to definitively tie it to Age of Ultron. =Agents of S.H.I.E.L.D. At the end of the first season, Phil Coulson was named the director of S.H.I.E.L.D. He will probably not appear in Age of Ultron. = Agent Carter. Marvel is producing an eight-episode series set around Agent Carter following WWII. It will air during Agents of S.H.I.E.L.D.’s mid-season hiatus. It’s unclear how closely it will tie in to Age of Ultron.