Deep within the depths of space, the planet-killer Unicron carves a nightmarish path of death and destruction en route to the planet of Cybertron. Meanwhile, a ruthless surprise assault on their City by the Decepticons leaves the Autobots leaderless. Hunted by Unicron's relentless agent Galvatron, the Autobots travel to distant planets and meet new foes and new friends. With the fate of the Autobot Matrix of Leadership and Cybertron itself at stake, can one heroic figure rise forth and light this most darkest hour?