In Jasper, Nevada, three young humans, Jack Darby, Miko Nakadai, and Rafael Esquivel, are accidentally caught in the crossfire in a fight between enormous robots that transform into vehicles. They are taken to the base of the Autobots, where Autobot leader Optimus Prime explains that he and his team, Arcee, Ratchet, Bulkhead and Bumblebee, are bio-mechanical aliens from the planet Cybertron, and not long ago the Autobots had a devastating war against the warlord Megatron and his followers.