In the year 2005, a brutal civil war between the Autobots and Decepticons rages on the planet Cybertron. The Decepticons, led by the tyrannical Megatron, have conquered Cybertron's capital, forcing the Autobots to operate from scattered bases as they plan to retake their home. Optimus Prime learns of a new Decepticon assault on the Autobot city on Earth and races back to defend it. The Autobots valiantly fight against the overwhelming might of the Decepticons who seek to capture Earth's resources to forge the ultimate weapon and finally crush the Autobots’ resistance.

As the battle spills from Cybertron to Earth, both factions suffer heavy casualties. The Autobots, facing desperation, hatch a plan to launch a counteroffensive to reclaim Cybertron, but the Decepticons intercept this plan and a fierce skirmish ensues in space. During these dire times, an ancient and colossal menace looms over both Autobot and Decepticon, threatening to devour all in its path. This new, seemingly unstoppable force pushes the Autobots to find new allies and heroes amongst their ranks, while the Decepticons vie to harness this power for their own conquests. With their existence in peril, the Transformers must confront their greatest challenges and sacrifices in the face of this monumental threat.