The Decepticon leader Megatron returns from a three-year exile with a plan to exploit the properties of a mysterious substance called "Dark Energon", which has the ability to turn the bodies of dead Transformers into zombie-like Terrorcons. The Autobots storm an Energon mine in search of their lost comrade Cliffjumper, only to discover that his dead body has been revived as a ravenous zombie by Dark Energon.

Debuts: William Fowler, June Darby, and Decepticon Miners

Bulkhead, Arcee and Bumblebee sneak on to the Decepticon warship, the Nemesis, to rescue Agent Fowler, while Optimus Prime and Ratchet fight off Megatron and a horde of Dark Energon zombies.