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.
Bumblebee questions his worthiness to his team after he is compromised.
Bumblebee discovers that MECH and Starscream are responsible for his troubles; Ratchet confronts demons from his Cybertronian past.
Wheeljack returns to Earth, hot on the the trail of Skyquake's brother Dreadwing.
Megatron sends Dreadwing, Airachnid and Breakdown to investigate the trail of a potential Energon source, but what Airachnid doesn't know is that Dreadwing and Breakdown have actually been ordered to kill her for her treachery. She eventually catches wind of this, however, killing Breakdown and running off into the woods. Upon arriving at an abandoned Energon mine, Airachnid encounters Starscream cowering from a large Insecticon. After using her abilities to control the creature, she contacts Megatron and tells him to come to the mine, planning to use the Insecticon to kill him so she can claim Decepticon leadership...
Following from the events of the previous episode, Agent Fowler is sat down to explain recent events to his superior, the cynical and disbelieving General Bryce. Threatened with a military tribunal and Team Prime's termination, Fowler tries to convince the General that the Autobots are still on the military's side, but the General believes that Optimus Prime went rogue and has perished, failing to fully understand that Nemesis Prime was not the real Optimus.
Bulkhead is trapped on the Decepticon Warship and amid dual tries on Megatron's life.
Megatron infuses The Nemesis w/ his own supply of Dark Energon which results in the ship taking on a life of its own with its own agenda. Meanwhile Optimus reluctantly decides to use the Spark Extractor in an attempt to bring the war to an end.
Megatron goes on a conquest to reveal the rest of the relics while Arcee and Bumblebee race him to New York City before Megatron gets there.
Optimus Prime travels to Antarctica to hunt down the second relic, but while there he is confronted by Dreadwing and Starscream, and finds himself caught between shifting alliances.
During a relic hunt, Ratchet and Wheeljack get a one-of-a-kind opportunity when Soundwave's flying minion, Laserbeak, is disabled.
Bulkhead, on mission for the fourth relic, came back in critical condition via ground bridge. What happened?!? One epic showdown as Bulkhead and Hardshell go head-to-head in the ongoing quest to gather the last of the Iaconian relics on Earth.
Still reeling from the near-fatal experience Bulkhead faced at the hands of Hardshell during the last relic hunt, Wheeljack and Miko decide to take matters into their own hands and leave to hunt down Hardshell to exact revenge for their friend.
When Arcee is unexpectedly brought back into the company of an old friend, they discover together that Decepticon has been scheming behind their backs an elaborate plan with the intentions of destroying the Autobots and claiming his victory.
Optimus Prime and Megatron once again face each other in an epic battle for control over the Earth; the Autobots and Decepticons come across some clues that could have the potential to change the war and perhaps restore Cybertron. Starscream goes on a quest for Red Energon; a new Autobot joins Team prime.
After being granted a new start in his life, the ever stone-faced Silas begins to see the world in a new light and makes an out-of-character decision to go to Megatron in the hopes that he will be allowed to join the ranks of Decepticon.
Now that the location of the relics have been exposed by Orion Pax, the race is on to find the next one. New recruit Smokescreen and Jack are on the job with the Autobots looking to cut down Megatron before the beats them to it.
The Autobots find out about the Omega Keys and their secret. Meanwhile, Megatron attempts to control the power of the Primes.
As the race for the Omega Keys grows more desperate, Knock Out harnesses the power of sound, and Starscream the power of hyper-speed.
When the Decepticons take him captive, Smokescreen learns of the location of the final Omega Key - and attempts to retrieve all of the other stolen keys from Megatron.
In an effort to secure a peaceful truce that would be beneficial to all parties involved, Starscream offers Megatron a ceasefire but Dreadwing has other ideas and does whatever he can to keep the diplomatic agreement from taking place.
The Autobots and Megatron's Decepticons are drawn into Cybertron to face each other in a heroic battle over their mutual quests for the coveted Omega Lock, which, once unlocked with the four keys, would reawaken Primus'