The Ultimate Doom, part 1

In a part of India a new solar power plant has been created and it means that enercy can be created from the sun in no time at all. As it is tested for the first time everything is going fine until a sudden explosion happens and in step Starscream, Thundercracker and Skywarp who wouldn't mind getting some energy for themselves.
 

A group of Autobots just happen to show up though but the entire thing is being watched by Megatron and his new human ally Dr. Arkeville, and this entire set-up is just a diversion. Megatron then contacts Soundwave who is standing outside Autobot HQ and sends Rumble and Ravage inside the base to distract the other Autobots whilst giving Laserbeak enough time to capture one of the humans there. Laserbeak ends up grabbing Sparkplug before Spike can stop him.
 

Sparkplug is taken back to the Decepticon base where Dr. Arkeville shows off his invention - the hypno chip. Sparkplug says that the Autobots will stop whatever it is that the Decepticons are up to, but Megatron silences him and then tells him that he will be the very first in a new breed of slaves.
 

Spike's down in the dumps because he's got no idea why the Decepticons have taken his father. But the Autobots are already going to try and get him back and Prowl quickly cooks up a plan involving them heading straight to the Decepticon underwater base. Optimus gives the order and the Autobots transform and roll out.
 

At the Decepticon base once more Megatron and Shockwave talk about using the space bridge to transport a "special cargo" from Earth to Cybertron, although Shockwave is weary of this as doing it involves using up all the energon he has left. Dr. Arkeville overhears their conversation and tries to learn more about what it is they're doing but Megatron basically tells him to mind his own business and then demands a demonstration of the hypno chip. Dr. Arkeville shows how he can control people with the chip and gets Sparkplug to knock over a model of Optimus Prime.
 

A group of Autobots arrive and several of them jump into the ocean to attack the Decepticon base whilst Brawn leads another group through a cave and starts to drill though it to secretly enter the base from underneath. Meanwhile Optimus Prime leads everyone else towards the base to distract the Decepticons and give Brawn enough time to complete his mission.
 

The Autobots open fire and soon enough the Decepticons appear to counter attack. Meanwhile Brawn's small group enters the Decepticon base and soon finds Sparkplug and all four of them escape before any Decepticons can stop them. All the Autobots regroup and head back home but the doctor is pleased as they've taken his slave into their midst.
 

Back at the Autobot base Spike is happy once again now that his Dad is back but he sees him acting weirdly -going around fixing Autobots, even ones that don't need repairs done to them. All of this is somehow being watched by Arkeville and as Sparkplug fixes Optimus Prime a laser blast from behind is heard and Megatron and the Decepticons enter the base to attack.
 

The Autobots try to fight back but none of their weapons work -Sparkplug's repairs have done nothing but short-circuit everything and make them sitting ducks for Decepticon fire. Spike then finds out that his Dad has messed around with Teletraan-1 so the alarms didn't go off, but to save the Autobots he makes the computer deploy a lot of fire-retardant foam on the Decepticons which Megatron says could permanently damage them, so they pull out.
 

Sparkplug then offers Spike the chance to join him and work on the side of the Decepticons, but his son refuses and so he tells him that the next time they meet, they will be enemies and then runs off. Later on the Decepticons gather around a large site where three giant pylons have been created. Starscream brings Arkeville and Megatron reveals his bold plan -to bring Cybertron itself over a space bridge! Naturally Arkeville is concerned as it means that this will result in all kinds of natural disasters happening such as tidal waves, but Megatron says this is part of the plan - it will generate lots of energy the Decepticons can take.
 

The Autobots fix up Teletraan-1 back to normal and send out a sky-spy which soon finds the Decepticons. The Autobots also get to see the three large machines and Teletraan-1 scans them, revealing that these machines have enough power to generate the biggest space bridge ever seen. Optimus and the others roll out to find out more.
 

The Autobots reach where the Decepticons are and are about to attack when Megatron has Arkeville send out a whole batch of slaves upon the Autobots. Optimus runs past them but the humans then pick up primitive weapons and run to and attack all of the other Autobots who can't defend themselves as they know they can't hurt them.
 

As the humans keep the Autobots busy, Sparkplug activates the first pylon whilst Thundercracker turns the second one on. Megatron tries to switch on the final pylon but is stopped by Optimus, who tells him to give it up. But Megatron says he won't be activating it, instead, Prime will - or Cybertron will be destroyed forever.
 

Not wanting to lose his home planet, Optimus turns on the third pylon and this creates the large space bridge needed to transport Cybertron from one galaxy to another. The operation is a success and soon Cybertron is above the Earth and a strong wind picks up much to the delight of Megatron, who says that this is just the beginning. The first part of the Ultimate Doom trilogy ends with Optimus Prime worried that whilst he has saved Cybertron, he has endangered the Earth.

The subtitle for this episode is "Brainwash" as seen in the script.

How exactly fire-retardant foam is the Decepticons' Kryptonite is unexplained.