While Wanda & Pietro are training,Tony & Steve came to see Nick Fury,who shows them Hammer's file of a hidden base which is called Project Ultron. The Avengers went to the hidden base,only to find a robotic body. After they took it from the mansion,The robot came alive,introducing himself as Ultron,who beckoned the Iron Legions to attack the Avengers. They took out one & Ultron as well,but his consciousness escape to the other drone. He reveals that Loki had Hammer invented him with the power of the Mind Stone and escapes.
Ultron begun building an army so they be powerful enough to take over. The Avengers soon learned of Ultron's location. They infiltrated the base and took out the Sentries. They extracted the Mind Stone and two of Ultron's creations. They begun to use the mind stone on one of them,reprogramming a female Android,who is named Jocasta. Ultron begun the assault with his army. joins the Avengers to battle against them with Quicksilver & Scarlet Witch's help. Jocasta successfully reprogram Ultron's other creation,naming him Vision.
The Avengers keeps on fighting and confronts Ultron,but gets overpowered. Vision appears and shut him down,allowing Thor to strike his head off. They release a public apology to the Ultron incident and Vision wants to know what is like to be an Avenger.
Mid-Credits:
A bunch of mercenaries found Ultron's head on the beach.