The Dweller in the Depths

While things are good for the Autobots on Cybertron's surface, the planet's barren core proves to be home to dark things of considerable power. The Quintessons know exactly what is down there and want to release them, but they can't do so on their own. They trick Galvatron into doing it and disaster results. The dangerous Trans-Organics soon run rampant, and one the Dweller begins taking over every Autobot and Decepticon in sight.