Mysterious attacks on America's maximum security prisons leads to mass outbreaks of super villains, causing Iron Man, Thor, Wasp, Henry Pym, and the Hulk to team together in order to stop them.
The Avengers discover the frozen body of Captain America and revive him, leading Baron Zemo to attack, seeking revenge against Cap for infecting him with Virus X.
Furious at Tony Stark for buying up his company, Simon Williams seeks revenge by undergoing a dangerous AIM procedure, overseen by MODOC and the Grim Reaper, Williams' brother, which turns him into a being of pure ion energy.
The Black Panther seeks the Avengers' aid in freeing his African nation of Wakanda from usurper king Man-Ape, and stopping Hydra agents Ulysses Klaw and the Grim Reaper from stealing Wakanda's supply of vibranium.
When the Leader creates a bubble of gamma radiation emanating from the Cube that mutates any human it touches, the Avengers team up with Doc Sampson to stop him. Meanwhile, Hawkeye infiltrates a Hydra base in order to capture Black Widow.
It's up to Hawkeye, the Hulk, and Thor to save the day when the Leader's gamma radiation ray mutates the rest of the Avengers and threatens to do the same to every human on earth.
It's Hawkeye, Black Panther, and Ant Man to the rescue when Baron Zemo and his Masters of Evil defeat the rest of the team and take over the Avengers Mansion.
Defying the orders of both SHIELD and Iron Man, Hawkeye and Mockingbird allow themselves to be captured by Hydra in an attempt to bring down Black Widow.
Kang launches a full-scale invasion of Earth using an army of robots, and in order to save New York, the Avengers are forced to unleash the Ultrons who serve as guards for the Negative Zone Prison.
Despite Thor going missing and Captain America ending up in the hospital, the Avengers must stop Ultron from eliminating the world's most flawed creatures-humanity.