Loki's scepter, remnant from the first crossover film, which had been used for its power to draw forth two more beings of inordinate ability and skill in twin brother and sister Pietro and Wanda Maximoff, a speedster and telekinetic mind-warper, respectively. After the battle, the Avengers end up with the scepter's possession, which Tony Stark uses to try to create an army of artificial-intelligence entities that will work to shield Earth from possible alien threats in the future. However, the first AI creation emerges, and its belief is that to protect Earth from harm (as Tony puts it, achieving "peace in our time"), that means eradicating the ones most responsible for its perilous situation -- humans. It's now up to the Avengers to keep this new entity, dubbed "Ultron", from succeeding in its mission of protection