THE COMING OF THE...WONDER MAN!
Baron Zemo, the Executioner and the Enchantress scheme on how to defeat the Avengers. They notice in the news that Simon Williams, arrested for embezzling money, blames Tony Stark. They agree to help him get revenge on Stark as Iron Man is his bodyguard (they are unaware they are one and the same). They take Williams to the Amazon jungle and use a machine on him which makes him all-powerful, but to keep him under control, Zemo poisons him and only he knows the antidote.
They stage a battle against the Avengers in that Wonder Man comes and aids the Avengers to earn their trust. He then explains the illness he has and the Avengers help to find a cure. The Wasp is taken captive and the Avengers go to save her only to be betrayed by Wonder Man. The Masters of Evil come very close to defeating the Avengers when Wonder Man decides to betray them as the Avengers did all they could to save him even though they didn't know him. Wonder Man saves the Avengers then subsequently dies from the poison.