Unicron awakens, threatening to destroy the planet Earth, which is revealed to have formed around his very body in prehistoric times. He rejects Megatron as his servant, and decides to take matters into his own hands to finally fell the last of the Primes, Optimus.

The Autobots and Megatron fight their way to Unicron's spark chamber. Meanwhile, Ratchet tells the kids about Cybertron.