Ratchet concludes his tests on Optimus Prime and gives their leader a clean bill of health. Optimus thanks Ratchet and Bumblebee, while Arcee expresses her doubt as to whether she managed to successfully end Megatron's life during their mission on the Decepticon ship. In truth, and unknown to any of the others, Megatron's psyche still dwells in Bumblebee's processor, and he's determined to reclaim his own body.
While at the base, Miko referees a basketball game between Bumblebee and Bulkhead. Bulkhead easily sinks the first basket, but as Bumblebee goes to shoot, he suddenly flashes back to the Space Bridge explosion. When Bulkhead interrupts the vision, he gets the ball thrown at his head. Bumblebee apologizes and they play on.
Later on, Bumblebee freezes as Megatron takes control. Megatron wonders how he escaped the destruction of the Space Bridge, and he recalls Starscream pulling the sliver of Dark Energon from his chest. Now knowing what he needs to restore his body, Megatron vows to take revenge upon his subordinate.
On the Decepticon warship, Starscream taunts Megatron's body with the Dark Energon sliver, announcing that he has come up with a new, epic plan that will convince the other Decepticons that he's worthy of leadership. Knock Out arrives in time to hear the tail end of the speech.
Waiting outside his house, Raf calls Jack, who is already in class, to complain that Bumblebee hasn't picked him up for school. Bumblebee is still at the Autobot base, being puppeted by Megatron to crush a piece of equipment. Ratchet is irritated by the destruction, and Bumblebee explains his visions of Megatron. Ratchet induces a power-down to allow Bumblebee's mind time to rest. While he's explaining this to Optimus and Raf, they get a call from Agent Fowler, who says that Decepticons have broken into the Kauai Naval Observatory in Hawaii and stolen the Heuck Nigoghossian telescope's primary lens. Fortunately, the lens has a tracking device, and the Autobots trace it to the Arctic, where there's a massive, unmineable Energon deposit — unmineable unless the glacier it's in is melted, something that would devastate coastal cities.
Indeed, the Decepticons have already created a heat ray with the lens, and Starscream begins melting the glacier in question.
At the Autobot base, Raf chats with the shut-down Bumblebee, despite Ratchet pointing out that Bumblebee can't hear him. Raf asserts that Bumblebee is family and shows off a photo of his parents and siblings.
Meanwhile, Optimus, Arcee and Bulkhead walk through the Arctic and locate the Decepticon warship, which is warming things up with its heat ray.
At the base, Ratchet leaves Raf and Bumblebee to find parts to repair the equipment Bumblebee damaged. While he's gone, Bumblebee suddenly powers up and heads to the main control room, where he activates the Ground Bridge. Ratchet and Raf are surprised to find him departing through the Ground Bridge and wonder where the diminutive Autobot is going. Under Megatron's control, Bumblebee arrives at the battlefield where Optimus and Ratchet once fought Megatron's army of Terrorcons, in search of the Dark Energon shard Megatron used to raise the dead. Ratchet attempts to use the Ground Bridge to follow Bumblebee, but once he activates it, Bumblebee promptly steps back through, carrying the Dark Energon, and decks the medic. Bumblebee briefly reasserts control to place Raf out of the way before Megatron forces Bumblebee to run back through the Ground Bridge. Ratchet realizes that Megatron's mind has taken over Bumblebee, and he tracks the scout to coordinates in the Arctic. Raf insists on going, too.
Atop the Decepticon warship, Starscream spots Bulkhead and Arcee. Knock Out orders Breakdown to deal with the two Autobots, and the big 'Con starts laying into them. Meanwhile, the unseen Optimus scales a nearby cliff.
Ratchet and Raf arrive in the Decepticon ship to find disabled Vehicons everywhere. They reach the lab, where Bumblebee has hooked himself up to Megatron's body, but when Ratchet attacks Bumblebee, he's knocked across the room. Raf manages to encourage Bumblebee to retake control of his mind and body, but it's only a brief respite. Ratchet yanks the life support cable from Megatron, only to again be tossed across the room. Despite a last-ditch attempt by Raf to stop Bumblebee, the scout plunges the Dark Energon shard into Megatron's body, and Megatron awakens. A group of Vehicons arrives to find Megatron has risen from the dead, and he orders them to terminate the Autobots, as he has his own "extermination to perform". Under fire from the Vehicons, Ratchet, Bumblebee and Raf retreat.
Optimus reaches the top of his cliff and takes a flying leap onto the Decepticon ship. On the ground, Arcee and Bulkhead continue to battle Breakdown. Starscream and Knock Out spot Optimus coming towards them across the hull of the ship, and Starscream turns the heat ray on the Autobot leader. Undeterred, Optimus drives all the way up to the heat ray and slices it with his sword, causing the whole thing to explode. Optimus is thrown to the ground, only to face the rage of Starscream, who begins diving towards him, missiles at the ready, declaring that allowing Optimus to live was Megatron's "greatest mistake". Just before Starscream can fire, he's intercepted by Megatron, who takes his disloyal lieutenant back to the Decepticon warship. Faced with his old leader, Starscream attempts to flee in his vehicle mode, only for Megatron to grab him by the tail and toss him against the ship. Even the promise of nearby Autobots to destroy - including the still-stunned Optimus - isn't enough to distract Megatron from his wrath; he mocks Starscream before dragging him away by the head.
Watching the still-blazing ship depart, Optimus radios Ratchet for a bridge, but Ratchet, Bumblebee and Raf appear nearby.
Later at base, Ratchet finishes checking over Bumblebee, who thanks Raf for helping to rescue him.
* BrainwashedAndCrazy: Poor 'Bee.
* ContinuityNod: Arcee is especially exasperated that Starscream's big scheme is in the arctic. [[Recap/TransformersPrimeS1E7Scrapheap Considering what happened episodes ago...]]
* DemonicPossession: Well, Megatron sure looks/acts like a demon.
* HesBack: Villainous version. Arcee even says it word for word.
-->'''Megatron''': Decepticons! Your rightful lord and master has returned!
* IKnowYoureInThereSomewhereFight: Raf tries. He really does.
* IronicEcho: Megatron taunts a groveling Starscream with the latter's words from only moments before.
--> '''Starscream:''' The Autobots...Optimus...right there...waiting for you!
--> '''Megatron:''' My 'greatest mistake'? I've made a few. But there is one I do not intend to make again!
--> '''Fowler:''' Prime, you spot any Decepticons wearing hula skirts lately?
--> '''Starscream:''' Lord Megatron? You are...you're healed! Praise the [=AllSpark=]! It is a miracle!
--> '''Megatron:''' Oh, it will be a miracle all right, Starscream...if you survive what I have planned for you!
--> '''Breakdown:''' I'm gonna put you on ice!
* VillainousRescue: Megatron stops Starscream just before he can finish off Optimus. Half because [[TheOnlyOneAllowedToDefeatYou that honor is his alone]], and half because he intends to punish Starscream.