The Autobots go in search of Cliffjumper, whose life signal is weak and find Megatron wielding the dangerous dark Energon.

Airachnid makes a deal with Silas to get revenge against Arcee and Jack.

The Autobots try to claim a magnetic weapon before the Decepticons get to it.

The Decepticons quickly try to build a space bridge before a prophesied darkness arrives.

Earth has an outbreak of natural disasters, caused by Dark Energon.

The Autobots acquire a surprising ally in their battle to save Earth.

The Autobots go to the Earth's core to fight for the planet; and Jack uncovers info about Optimus' background.

Megatron manipulates the impaired Optimus into joining the Decepticons.

Jack learns how to restore Optimus' memory.

Optimus begins to piece together his real identity using several clues (including Starscream referring to his as a "prime" -- whoops!), and eventually rebels against Megatron’s orders. Meanwhile, Optimus' Autobot pals hatch a risky plan to get their leader back.

Due to Megatron's crafty plan, Optimus must make a hard decision which could affect the whole Autobot team.

While Optimus struggles to survive after Megatron’s destruction of the Autobot base, the separated members of Team Prime try to reconnect.

The Ultimate Autobot Hunter is unleashed on our heroes.

Unlikely duos team up, including Acree and Wheeljack, and Agent Fowler and Jack's mom.

The Autobots face the Decepticons for a final showdown.