Ultron wakes, destroys J.A.R.V.I.S. and attacks the Avengers before fleeing with the scepter. He builds himself a stronger body and recruits the Maximoff twins, who blame Stark for the death of their parents. The team clashes with Ultron's forces, and Wanda uses her mind powers to torment the heroes with visions.
In Johannesburg the Hulk is manipulated into a rampage, and Stark has to stop him with his Hulkbuster armor. The destruction leads to public anger at the team, so the Avengers hide at Clint Barton's farm to regroup. It is a quiet middle stretch, and it gives Hawkeye room in the story.
Ultron then goes to Seoul to steal a synthetic body made with the help of Dr. Helen Cho. Wanda sees his true plan, which is extinction, and the twins turn against him. The Avengers take the body, and Stark and Banner upload J.A.R.V.I.S. into it, creating Vision.
The finale is set in Sokovia. Ultron lifts a large part of the capital into the air with a machine so it can crash down and wipe out life on Earth, and the Avengers fight his army of drones while they evacuate civilians. Pietro is killed shielding Barton from gunfire, and Wanda destroys Ultron's main body. A remaining drone restarts the machine, but Stark and Thor overload it and shatter the city before it hits the ground. Vision destroys Ultron's last copy, and the surviving Avengers go their separate ways.
The loss of Quicksilver, played by Aaron Taylor-Johnson, is the emotional hinge of the last act, because it pushes Wanda from grief into the force that ends Ultron's main body. Afterward Thor heads to Asgard to look into the Infinity Stones while a new Avengers team begins to form, and the villain who looms behind all of it is Thanos.
