It is the year 2007, and though life is peaceful for the Autobots, Optimus Prime has seen worrisome visions of the future. In their first movement in months, the entire Decepticon armada attacks Autobot City on Earth in search of the Key to the Plasma Energy Chamber, a volatile energy source. With the key in hand, Galvatron leads his forces to Cybertron, where he sends Scourge deep into the planet to activate the Plasma Energy Chamber. A surge of Plasma Energy strikes an Autobot shuttle, sending it and its crew of 12 clear across the galaxy where it crash lands on the planet Nebulous. There the Autobots learn of the Nebulan civil war with their evil masters, the Hive. The battle reaches a new level when five of the Autobots volunteer to merge with five Nebulans, creating a breed of Transformers: The Headmasters!