High-school student Sam Witwicky buys his first car, who is actually the Autobot Bumblebee. Bumblebee defends Sam and his girlfriend Mikaela Banes from the Decepticon Barricade before the other Autobots arrive on Earth. They are searching for the Allspark, and the war on Earth heats up as the Decepticons attack a United States military base in Qatar.

Sam and Mikaela are taken by the top-secret agency Sector 7 to help stop the Decepticons, but when they learn the agency also intends to destroy the Autobots, they formulate their own plan to save the world. An ancient struggle between two Cybertronian races, the heroic Autobots, and the evil Decepticons, comes to Earth, with a clue to the ultimate power held by a teenager.