The superhero team is dealing with a threat of their own making: a sentient robot called Ultron (voice of James Spader), who was originally designed as part of a peacekeeping program. Captain America (Chris Evans), Iron Man (Robert Downey Jr.), the Hulk (Mark Ruffalo), Thor (Chris Hemsworth), Hawkeye (Jeremy Renner), and Black Widow (Scarlett Johansson) have been working to take down various cells of a secret society of villains known as HYDRA. Their zeal to make the world a better, safer place inspires Tony Stark, genius billionaire and alter ego of Iron Man, to create Ultron in order to respond to additional threats that the Avengers aren't able to handle. Ultron, unfortunately, takes this directive way too seriously -- he believes that world peace can only be achieved by exterminating humanity, and he'll stop at nothing to accomplish this goal.