While manufacturing the body he would soon inhabit, Ultron tries to escape from Korea, the chamber creating his body safely loaded into a cargo truck. The Avengers, being friends with the possessed doctor, discovered Ultrons plan. Meanwhile, with Ultron now uploading his consciousness into an organic body, Scarlet Witch is able to read his mind in the same way that she can with organisms, although she was unable to do this before, because Ultron inhabited a robotic form. Scarlet Witch sees the devastation Ultron wishes to cause, and confronts him. Ultron attempts to convince her that it’s for the greater good, and she pretends to go along with it, using her abilities to snap the South Korean doctor out of Ultrons trance. Scarlet Witch and her brother, along with the doctor turn on Ultron all at once in an attempt to help The Avengers. Ultron becomes fed up and kills the doctor, attempting to do the same to the mutants he once worked with, but they were able to escape. Ultron takes to the streets, realizing that he will have to find a new place to begin his upload. The Avengers follow him, managing to secure the vibranium organism, but allowing Ultron himself to escape.
Back in the Stark tower, which now acts as The Avengers Headquarters, they discover what Ultrons purpose with the body was. Tony makes a risky decision, and manages to get Bruce on board with it. With the rest of the group trying to stop him, Tony creates a new AI on the spot based on JARVIS’ framework, and uploads it into Ultrons vibranium body, creating the Vision. Vision bursts out of his containment and attacks The Avengers in an animal-like frenzy. He then calms down, floats over to the window and observes for a few seconds (did I mention he can fly and has other incredible powers because Lokis infinity stone is implanted in his forehead?) before turning to The Avengers and chatting with them. They discover that Ultrons plan is to lift a chunk of city out of the Earth, only to send it plummeting back towards the rest of the city in order to cause an incredible shockwave.
The Avengers rush to the same Russia-esque nation in which Quicksilver and Scarlet Witch were born and raised, finding Ultron. His plan goes into fruition, the chunk begins to float upwards towards the sky. The Avengers have none of it, going in to attack all of Ultrons duplicate henchmen and waging an all-out battle on the levitating rock. The Avengers soon come near the end of the battle, realizing that the robots they had been fighting were simply distractions from the fact that they were fighting on top of a massive weapon. Soon, SHIELD (Strategic Homeland Intervention, Enforcement and Logistics Division) shows up with a plethora of “Heli-Carriers,” massive, Aircraft Carrier-like floating ships to bus civilians out of the fray. Captain America smiles on as he sees what SHIELD was always meant to be. While the evacuation of both the levitating rock and the town below it are taking place, Pietro Maximoff, or Quicksilver gives his life saving a young boy from one of Ultrons henchmen. Wanda watches her brother die, and decides to go back for Ultron. She finds Ultron, lying in a broken traincar, and snappily shows Ultron what he did to her by physically ripping his “heart” from his chest and stating that she was “already dead” after watching her brothers death. The frail and damaged Ultron is then found later on in the woods, near the destroyed town, by Vision. Vision and Ultron discuss how humanity is doomed by their own stupidity, Ultron disapproving of Visions sufferance towards the humans. While they are talking, Ultron attacks Vision, resulting in Ultrons swift and clean demise.