With the rising threat of HYDRA, the Avengers were officially reassembled, with the financial backing of Tony Stark. Using the former Stark Tower, now renamed Avengers Tower, as their headquarters, and using the new drones of the Iron Legion, they embarked on several missions to ruin HYDRA's plans for world domination. Their main target was the cell of Baron Wolfgang von Strucker, which was in possession of Loki's scepter.
Thanks to information acquired by Phil Coulson and S.H.I.E.L.D. who gave it to Maria Hill, the Avengers were able to finally locate Loki's Scepter in the European country of Sokovia. The team attacked the base in force. The team fought as a unit, using skilled combat techniques which complemented each others' fighting styles. This synergy, coupled with their abilities and equipment, gave them a decisive advantage over the HYDRA defenders. During the battle, the superpowered Maximoff twins Pietro and Wanda also attacked the team and Hawkeye was injured in the process. Tony located the Scepter but as he went to retrieve it Wanda used her powers to show Stark his greatest fear: the entire team dead and the Chitauri invading Earth. Stark retrieved the Scepter and the team returned to the Avengers Tower.
Stark convinced Thor to let him study the Scepter for the next three days. Then he persuaded Banner to help him merge the Ultron Program with the artificial intelligence inside the gem on the Scepter. Three days later, their experiments were still unsuccessful. That night, the Avengers, Maria Hill, Helen Cho and James Rhodes were having a party, as they tried to lift Mjølnir. Unknowingly to Stark, the Ultron Program successfully reacted when exposed to the power of the gem, creating the new artificial being, Ultron. After making a body from the damaged parts of the Iron Legion robots, Ultron appeared on the party, proclaiming that humanity was not worthy of survival. The Iron Legion, controlled by Ultron, attacked the Avengers, and although most of the robots were destroyed, including Ultron, one robot managed to escape with the Scepter, while Ultron's consciousness escaped via the internet.
The team flew to South Africa where they found Ultron, along with Pietro and Wanda Maximoff, taking the Vibranium. They engaged in a fierce battle, with Stark taking on Ultron alone while the rest of the team fought the Ultron Sentries and the Maximoff twins. Eventually, Stark brought down Ultron and destroyed his body. However, the team had been mentally taken down by Wanda Maximoff, who showed them their worst fears. She caused Bruce Banner to transform into the Hulk in the middle of South Africa, and the Hulk started to destroy everything he could. Stark called for his Mark XLIV armor and the; he tried to contain the Hulk in an enforced metal cage, but when this failed, the friends began to fight. Eventually, Stark knocked the Hulk down, but not without collateral damage.
To relax from their fears they had seen, and to hide until Maria Hill finds Ultron, the team arrived to Clint Barton's Homestead, where they learned that Barton had a wife and two children. Thor quickly went to meet Erik Selvig so he could help him understand the vision he had been shown. Natasha Romanoff and Bruce Banner talked about their relations and Tony Stark and Steve Rogers argued about the reason Stark had created Ultron. Nick Fury was also in Barton's home and he talked with the team about their next move to stop Ultron. Banner then realized that Ultron wanted to improved his body, so he needed Helen Cho and the Cradle devise to create his ultimate body.
Captain America, Black Widow and Hawkeye flew with the Avengers Quinjet to Seoul to retrieve the Cradle with the synthetic body in it. Tony Stark went to the NEXUS base in Oslo to find the person who prevented from Ultron getting nuclear codes. During the fight in Seoul against Ultron, Wanda and Pietro Maximoff helped the Avengers against Ultron, after they had discovered that he wanted to destroy the human race. They helped Captain America to save civilians during the battle. Black Widow managed to take the Cradle and gave it to Hawkeye, but she was kidnapped by Ultron. Hawkeye was forced to fly to the Avengers Tower to give it to Stark. The twins convinced Rogers that giving the Cradle to Stark will cause more troubles because he, like Ultron, cannot see the different between saving the world and destroying it.
Tony Stark and Clint Barton returned to the Avengers Tower. Barton brought with him the Cradle with the synthetic body in it, and he went to search for Romanoff. Stark reveled to Banner that J.A.R.V.I.S., who was not destroyed by Ultron as he thought, was the person who prevented from Ultron to get the nuclear codes. Stark tried to convinced Banner to help him put J.A.R.V.I.S. inside the body. At first, Banner refused but Stark claimed that it was the only hope they got to stop Ultron. Banner then agreed to help him. As the two were almost finished, Steve Rogers with Wanda and Pietro Maximoff came and ordered them to shut it down. After they refused, the two and Barton fought against the three, but suddenly Thor came in and revived the synthetic body with his lightning. The living body jumped out and briefly attacked Thor until he looked out over the city, the living body apologized and called itself the Vision and claimed to wish to assist them to fight Ultron. Thor explained that he had seen the Vision in his vision and the Mind Stone, one of the six Infinity Stones, that is in the Vision's forehead. At first the team did not trust him, but as proof of his honor, Vision handed Thor Mjølnir.
The Avengers, alongside Wanda and Pietro Maximoff and Vision, found Ultron in Sokovia where Natasha Romanoff was held. Bruce Banner freed her from her cell while the Avengers evacuated the city. Tony Stark and Vision confronted Ultron and he revealed to them that he was planning to turn a part from Novi Grad into a meteor, lifted by Chitauri technology. The city was flying, and the Avengers fought against Ultron and his sentries. The Avengers got assistance from Nick Fury and Maria Hill with the Helicarrier and they helped with evacuating the city, and from James Rhodes who helped with the battle. The Avengers regrouped to prevent Ultron from pressing the key that would cause the meteor to fall, becoming an extinction level event, killing billions. Ultron managed to kill Pietro Maximoff, who sacrificed himself to save Clint Barton. Wanda destroyed the main body of Ultron to avenge her brother's death, but a sentry pressed the key and the meteor fell. Stark and Thor caused the meteor to explode and Vision destroyed the last body of Ultron.
Members:
Captain America
Iron Man
Thor
The Hulk
Hawkeye
Black Widow
Scarlet Witch
Quicksilver
The Vision
Supporting Cast:
Maria Hill
Helen Cho
Allies:
War Machine
Falcon
S.H.I.E.L.D.
Equipment:
Avengers Tower
The Quinjet
The Iron Legion
