Two races of transformable alien robots (villains Decepticons and friendly Autobots) arrive on Earth in search of a mysterious source of power. In the war that breaks out between the two races, men take sides with the Autobots. Sam Witwicky ( Shia LaBeouf ), a clever teenager, who only wants to conquer the beautiful Mikaela ( Megan Fox ), becomes the key to a war that can destroy humanity.