風靡全球的Marvel超級英雄：「鐵甲奇俠」、「變形俠醫」、「雷神奇俠」、「美國隊長」、「鷹眼」及「黑寡婦」將破天荒地雲集一堂！世界陷入毫無先兆的恐怖危機，國際和平秘密組織「神盾局」的費局長 (森姆積遜 飾) 見事態嚴重，心知已沒有人可獨力抵擋，於是組織一隊史上最強的正義聯盟，集結多位超級英雄頑抗到底，令地球免被黑暗勢力吞噬！
2012年，科學家在北極冰面上找到一架墜毀沉冰數十年的大型飛機，來到內部探查時發現一個被冰封住的藍紅星條的「盾牌」。回到1942年3月，二次大戰期間，挪威滕斯貝格遭受納粹科學秘密組織「九頭蛇」的大舉進攻，其首領約拿·施密特闖入一座教堂，尋獲一個封存多年的外星文物「宇宙魔方」，走前槍殺試圖警告他的修士後，摧毀整座村莊以實施滅口。
在《復仇者聯盟》一役後，「美國隊長」正在努力嘗試適應現代生活，但當神盾局的同伴遭受突如其來的襲擊時，他又再度捲入危害全球的龐大陰謀之中。「美國隊長」與「黑寡婦」聯手揭破陰謀，卻被超級殺手步步狙擊，雖得新盟友獵鷹 (The Falcon) 拔刀相助，同一時間他們卻發現真正的強敵原來是最意想不到的「寒冬戰士」…
發生《雷神奇俠》連串事件前，神盾局特工寇森開車往新墨西哥州途中停車入油。當他走入便利店找零食時，兩名持械劫匪闖入用槍指嚇夜更店員交出現金，更命令寇森要交出車匙；但這班劫匪很快就會發現，眼前這位文質彬彬的西裝友絕非等閒之輩。
The realm of magic is being threatened by the realm of logic, so Carolinus, the green wizard decides to shield it for all time. Ommadon, the evil red wizard, stands in his way. Carolinus then calls for a quest that is to be led by a man named Peter Dickinson, who is the first man of both the realms of science and magic. It is Peter's job to defeat Ommadon.
An artist, Steve Rogers, is nearly murdered by spies, looking for his late father's national secrets. He is saved during surgery when a secret formula is injected into him; this serum not only heals him but also gives him fantastic strength and lightning reflexes. To help him solve the mystery behind his father’s murder and bring those guilty to justice, a government agency equips him with a special motorcycle loaded with gadgets and an indestructible shield. Now armed, he battles against the nation's enemies as the Sentinel of Liberty, Captain America.
In the days of King Henry IV, stalwart young Myles and his sister Meg have been raised as peasants, without any knowledge of who their father really was. But one day, they journey to Macworth Castle. There, Myles falls in love with Lady Anne Macworth, makes friends and enemies, and learns to be a knight.