一股突如其来的强大邪恶势力对地球造成致命威胁，没有任何一个超级英雄能够单独抵挡。长期致力于保护全球安危的神盾局（SHIELD）感到措手不及，其指挥官“独眼侠”尼克-法瑞（塞缪尔·杰克逊 Samuel L. Jackson 饰）意识到他必须创建一个“史上最强”的联盟组织，云集各方超级英雄一起发威，才能拯救世界于水深火热，抵御黑暗势力的侵袭。于是由六大超级英雄——“钢铁侠”（小罗伯特·唐尼 Robert Downey Jr. 饰）、“雷神” （克里斯·海姆斯沃斯 Chris Hemsworth 饰）、“美国队长”（克里斯·埃文斯 Chris Evans 饰）、“绿巨人” （马克·鲁弗洛 Mark Ruffalo 饰）、“黑寡妇”（斯嘉丽·约翰逊 Scarlett Johansson 饰）和“鹰眼”（杰瑞米·雷纳 Jeremy Renner 饰）组成的 “复仇者联盟”应运而生。他们各显神通，团结一心，终于战胜了邪恶势力，保证了地球的安全。
Tony: What the hell? What just happened? Please tell me nobody kissed me.
Rogers: We won.
Tony: All right, yay! Hurray. Good job, guys. Let's just not come in tomorrow. Let's just take a day. Have you ever tried shawarma? There's a shawarma joint about two blocks from here.I don't know what it is, but I want to try it.
Thor: We're not finished yet.
Tony: And then shawarma after.
Loki: If it's all the same to you, I'll have that drink now.
News: Despite the devastation of what has been confirmed as an extraterrestrial attack, the extraordinary heroics of the group known as the Avengers has been to many a cause not only for comfort, but for celebration. It's just really great knowing they're out there. That someone is watching over us.
Citizen: I love you, Thor!
Citizen: And then these guys were like... And then the air goes... And this green guy walks up and he goes...
Citizen: I don't know.
Citizen: I don't exactly feel safer with those things out there. It just seems that there's a lot they're not telling us.
Citizen: Superheroes in New York? Give me a break.
Citizen: These so- called "heroes" have to be held responsible for the destruction done to this city. This was their fight. Where are they now?
News: Tough questions are being asked about the Avengers themselves. Their sudden appearance and equally sudden disappearance...
Citizen: What, this is all somehow their fault? Captain America saved my life. Wherever he is, and wherever any of them are, I would just. .. I would want to say thank you.
SHIELD: Where are the Avengers?
Nick: I'm not currently tracking their whereabouts. I'd say they've earned a leave of absence.
SHIELD: And the Tesseract?
Nick: The Tesseract is where it belongs. Out of our reach.
SHIELD: That's not your call.
Nick: I didn't make it. I just didn't argue with the god that did.
SHIELD: So, you let him take it and the war criminal, Loki, who should be answering for his crime.
Nick: I think he will be.
SHIELD: I don't think you understand what you've started, letting the Avengers loose on this world. They're dangerous.
Nick: They surely are, and the whole world knows it. Every world knows it. Was that the point of all this? A statement? A promise.
Maria: Sir, how does it work now? They've gone their separate ways. Some, pretty extremely far. If we get into a situation like this again, what happens then?
Nick: They'll come back.
Maria: Are you really sure about that?
Nick: I am.
Nick: Because we'll need them to.