Meanwhile, the Autobots have lost the home planet of Cybertron to the Decepticons, but are preparing for an assault that would take back their homeland.
After turning the tide of a devastasting attack on Autobot City on Earth and a final battle with Megatron, Optimus Prime passes on, and the Matrix of Leadership is given to fellow Autobot, Ultra Magnus. Unicron, for some unknown reason at first, is passionately displeased that the Matrix is around at all, and joins forces with a newly optimized Galvatron (formerly Megatron).
The story centers on the valiant and heroic struggle of a group of Autobots who must fight Galvatron's forces, Unicron, and unknown obstacles that lie along the way.
Tis a wonderful movie that if you haven't seen, you should consider checking out.