Scorponok runs rampant, easily smashing any Autobots out of his way. Zarak finds out Arcee has the plasma energy key, so he captures her (and Daniel in the process) before all of the Decepticons leave Nebulos and head to Cybertron. Optimus Prime has nearly all the Autobots board his ship so they can go after them, but Spike decides to stay behind and says he needs the help of Cerebros if they've got any chance in defeating Scorponok. Optimus is hesitant, believing Spike is the only one who stands a chance should the plasma energy chamber be opened, but eventually relents. Scorponok arrives on Cybertron, and the Decepticon Headmasters and Targetmasters quickly shoot down the Protectobots and Ultra Magnus.

When Galvatron finds out some of the Decepticons merged with organic beings, he's appalled. He wants to destroy them all, but the Targetmasters take aim at him. Zarak then appears, so Galvatron decides to talk with him. Later on, the Decepticons start harming Daniel, so Arcee gives Zarak the plasma energy key. Meanwhile, the Combaticons have constructed rocket engines onto Cybertron itself. These engines are activated, using the power packs from defeated Autobots. Cybertron heads to Earth.

The Autobots arrive and see Cybertron is missing, but Optimus realizes where Galvatron has taken the planet. The Autobots land on Cybertron and find out from Ultra Magnus that Galvatron intends to open the plasma energy chamber to destroy all of the Autobots, the Earth and the Sun. The remaining Autobots attempt to break into Scorponok, but are all captured. Galvatron sets a timer on the plasma energy chamber, with it to automatically open in 10 minutes. Meanwhile, Spike and Cerebros have used the Hive's old machines to create the incredible Fortress Maximus, a massive battle fortress. Spike is now a Headmaster himself, becoming the head of Cerebros, whilst Cerebros now becomes the head of Fortress Maximus. Fortress Maximus transforms to robot mode and battles Scorponok.

Fortress Maximus manages to knock Scorponok down, forcing him to transform to base mode. Cerebros enters Scorponok and saves all of the Autobots, but as they leave, the plasma energy chamber opens. The Decepticons get into Scorponok, who takes off and leaves, but is hit by a bolt of plasma energy and sent flying through space. On Cybertron, all of the Autobots are effected by the plasma energy. Spike shuts down the plasma energy chamber, but the energy has hit the Sun, causing it to go nova. Spike and the Nebulons reverse the rocket engine's polarity from output to intake, which sucks in all the plasma energy from the Sun and sends it into Cybertron.

The Sun is saved, and Cybertron is revitalized, entering a new golden age. The Autobots all recover, but Cerebros, no longer wanting to fight again, asks to be shut down. However once he sees the new Cybertron, he asks what happened. Optimus explains things, but says he doesn't have to fight any more. The Autobot Headmasters and Targetmasters return to Nebulos, where Optimus gives Cerebros a new mission: destroy the remaining Hive machines. Once this is done, Optimus tells Cerebros that he can stay here as the planet's guardian and live in peace. Meanwhile, the Decepticons manage to repair Scorponok. Galvatron says they have much work to do, intending to attack other planets and suck them dry of energy, in order to build a new planet a hundred times more powerful than Cybertron. He says he intends to rule the galaxy, to which Zarak says they will see.

Notes

-This is the final episode of the American Transformers series. It is believed that season four was originally going to be a much bigger season, and have more than three episodes, but plans were scaled back to just wrap things up with The Rebirth.

-Another rumor is that there were plans for the Japanese Headmasters series to be dubbed into English and aired in America instead, but the dubbed episodes were lost in a studio fire. Personally I really doubt this was the case, purely because that series kills off several characters, and Optimus Prime dies again within the first three episodes... I doubt Hasbro wanted even more backlash after what happened last time.

-Some of the voice cast were unaware that the series was even over. Dan Gilvezan (Bumblebee's voice actor) mentions in his book, Bumblebee and Me, that he only found out the series was over when Chris Latta (Starscream's voice actor) happened to meet him at a movie showing and told him. There was no wrap party either, and as Dan puts it, his time on Transformers ended "not with a bang, but a whisper".

Errors

-The opening recap claims Galvatron opened the plasma energy chamber in the last episode. Galvatron didn't even appear in the previous episode, and it was Scourge who opened the chamber in part 1.
-When Cerebros says he's had all the fighting he can stand, his eyes are colored gray instead of blue.
-The same issue happens again a little later on, when Cerebros asks Spike what he's looking for.
-When Cyclonus says they've got a real party going, Vortex is colored like Blades.
-Onslaught's eyes are colored gray instead of orange during this shot.
-When Fortress Maximus starts firing, yellow colored lasers are shown. But during the next shot, the lasers are colored pink.
-Cyclonus is shown to be in combat with the rest of the Decepticons when Fortress Maximus transforms, but later on, he's shown running out with Galvatron.
-When Optimus tells Spike the energy will kill them, the wrong background is used -a space background is used, they're supposed to be inside Scorponok.
-When Optimus is seen running out of Scorponok, his lower legs are colored white instead of blue.
-Cerebros has gray colored eyes again during this shot.
-During this shot, the wrong characters are shown in the background -instead of Gort and Arcana, Highbrow and Brainstorm are seen.
-When the Autobots starts celebrating, Bumblebee can be seen -and Goldbug is right next to him!
-During this shot, the Nebulons are the same size as Optimus Prime.
-As Cerebros says "it's a miracle", his eyes are yet again colored gray instead of blue.