At Avengers Mansion, Tony Stark explains the concept of a futurist to Steve Rogers as someone who either predicts or actively tries to create the next step that will make life easier, better and more advanced. Rogers seems skeptical about the idea before changing the subject to Tony's combat skills, or the lack there of according to Rogers. When it is clear that Stark is both insulted and incredulous, Rogers challenges him to some sparring/training in one-on-one, unarmed combat.
With the Hawkeye and the Hulk watching, Rogers and Stark suit up within a boxing ring. Rogers, using just what he has witnessed of how Stark handles super villains (ie, tackling and blasting), speculates that the man behind Iron Man has never actually been in a straight up one-on-one fight. Stark is challenged to merely punch Rogers, but every attempt is easily countered, ending with Stark flat on his face, much to Hawkeye and the Hulk's amusement. Stark grows defensive, arguing that with his armors are more than enough to give him the edge in any fight. Rogers counters that depending on his armors is a dangerous crutch.
Meanwhile, Thor, the Wasp and Ant-Man visit the Baxter Building, the home of that Fantastic Four. They bring with them in custody Blizzard, one of the criminals who escaped in the Vault jailbreak. The Avengers take Blizzard to Prison 42, a hyper security facility maintained by a group of Ant-Man's Ultron robots and located within a pocket dimension comprised entirely of anti-matter called the Negative Zone.
Back at Avenger mansion, Stark tries to explain to Rogers that the world has changed since the 1940s. Using advanced networking technology, Stark explains how he is able to use his Iron Man technology to assess the greatest dangers before him and the swifted way to neutralize them. Rogers still argues that training and preparation are worthwhile, no matter what year it may be.
Just then, a portal opens near Iron Man and Captain America, with Kang the Conqueror emerging soon after. He introduces himself, before attacking both of the Avengers. With Kang's technology advanced by over 2000 years, even Iron Man's most advanced defenses are easily deterred. Kang soon explains that he is not interested in attacking the Avengers as a whole but only Captain America, and how he traveled back in time to rescue his timeline.
Soon more of the Avengers join the fight against Kang, but Iron Man demands more information from the time traveling conqueror. Kang explains that in his time he is a omnipotent ruler, but a disruption in the space-time continuum was quickly wiping everything from existence out. The cause of the disruption was traced back to something that was never meant to exist in the 21st century: Captain America.
While the Avengers still fight to protect Captain America, Kang eventually decides to show the entire team a small taste of what the future holds if his mission is not successful. By pulling the Avengers ten years into the future, the heroes are able to see the destruction Kang spoke of. Earth is a vast, barren desert of nothing but sand and fires, the cities they once new reduced to rubble and ruins. Even global satellite networks have been disrupted, with not technological grid for Iron Man to tap into.
Kang explains that in the near future, Earth will become involved in a major war between two intergalactic empires, the Kree and Skrulls. Due to some intervention on Captain America's part, the final outcome of the Kree-Skrull war will be the sun's temperature being increased dramatically, causing the earth to become the burning desert the Avengers see now and completely unable to support human life. Kang's plan, in addition to eliminating Captain America from the new Earth timeline, also includes providing major weaponry capable of fighting off the upcoming dual Kree-Skrull invasion. A necessary component of this plan, however, is that Kang himself must conquer 21st century Earth before the invasions begin.
Captain America agrees to step down if it means that his part in the coming crisis can be averted. Iron Man also realizes that at least part of what Kang says is true given the Avengers past experience with the Kree,
and that Kang may be the world's best hope for survival...but it isn't worth bowing to such a clear tyrant. All of the Avengers--including Captain America--attack Kang in unison on Iron Man's orders.
After defending himself from the Avenger attack with his advanced technology, Kang attempts to desert the Avengers on the barren Earth by using his time-traveling chair to return to ten years prior without them. He is stopped, however, when cockroaches cover his body, the Hulk using the distraction to tackle him out of the time-traveling chair. While the Avengers keep Kang busy with seemingly futile attacks, Iron Man attempts to decipher exactly how the time-traveling features of the chair function. While initially baffled by the chair's advanced mechanics, Iron Man is finally able to find one piece of technology that he recongizes: a relatively ancient piece of Stark technology that allows him access through an obscure data port. By exploiting the data port, Iron Man is able to transport both the Avengers and Kang back to present day Earth.
Using his own chairs technology against him, Iron Man is able to disable Kang's protective suit to disable most of his defensive capabilities. Realizing just how vulnerable he is, Kang uses his suits last remaining system to transport both himself and the chair back to the Damocles, vowing that he isn't done with the Avengers. Iron Man and Captain America make it clear that they will be prepared for his return.
Aboard the Damocles, Kang reveals that his fleet does not simply consist of the main ship itself but also hundred of previously invisible flying saucers, all set to invade and conquer Earth.