The robot Ultron, wanting revenge on the superhero team the Avengers for constant defeats, places a document detailing their downfall in a time capsule.

When the time-travelling villain Kang the Conqueror finds the document centuries later, and having been thwarted by the Avengers himself, he travels back to their time to kill the team.

With many of the old Avengers such as Captain America, Thor, Iron Man, Quicksilver, and the Scarlet Witch either dead or missing, Hank Pym reluctantly forms another team.

Together Pym's team confronts Kang—now allied with Ultron, the new Grim Reaper and a creature called Oddball—and in a battle to the death, many of the Avengers are murdered before finally killing all the villains.

Hawkeye discovers that Captain America, who was formerly President of the United States and believed assassinated, is still alive and recuperating, and had watched the entire battle.