An evil robot named Ultron creates an android called the Vision and sends it to destroy Ant-Man, the leader of the Avengers. To get Ant-Man's attention, the Vision attacks the US President.
The Avengers must stop the Masters of Evil, who are trying to steal a shipment of highly dangerous government weapons. Meanwhile, Ant-Man feels threatened by the arrival of Captain America, a founding Avenger.
Vision volunteers to be "bait" to allow himself to be captured by Ultron as a way for the Avengers to track him to the villain's lair. But he finds himself torn between two loyalties.