The battle for Earth has ended but the battle for the universe has just begun. Sam Witwicky discovers something about the origins of the Transformers and their history on Earth after receiving visions from a remaining piece of the Allspark, where the story start before the pyramids were built, tying the Transformers to the beginning of human civilization.
After returning to Cybertron, Decepticon forces return to Earth on a mission to take Sam Witwicky prisoner. Worst thing came to happen, Megatron's dead body has been stolen from the US Military by Skorpinox and revives him using his own spark, and now Megatron is back seeking revenge with Starscream and more Decepticon reinforcements on the way. In the other side, by joining the mission to protect humankind, Optimus Prime lead the Autobots reinforcements form an alliance with international armies for a second great epic battle.