At the Decepticon HQ, Megatron yells at Soundwave for daring to disturb him just to watch a travel log Laserbeak and Buzzsaw are recording. Soundwave tells him to wait and observe, as he shows data revealing the location of a large underwater city. Megatron thinks this place much generate enormous energy, energy that shall soon be theirs.

The Decepticons head out and rendezvous with Laserbeak and Buzzsaw. They then dive into the water and quickly find the city, which Megatron finds intriguing.

Starscream decides to go in, despite Megatron's warning to wait, and leads Thundercracker and Skywarp. But the three of them hit some kind of shield located around the city, and bounce off. Megatron tells Starscream that rushing forward blindly is for dolts. A voice calls out saying that the land-stranger speaks wisely. It's Nergill, who is the King of Sub-Atlantica. He welcomes the Decepticons to his domain.

Soundwave says King Nergill is communicating telepathically, and his mental power is great. Starscream doesn't think it's as great as his firepower, but before he can shoot, he gets blasted by one of Nergill's troops. Nergill is disappointed, hoping they were different from other land creatures, but he sees they are not. He threatens to destroy them.

Megatron decides to show the boastful man-fish what he can do, and blasts at a cliff, sending rocks tumbling down and scattering Nergill and his forces. Megatron says Nergill is foolish, but he admires his war-like spirit. He believes they have much to offer one another.

Nergill telepathically talks to his troops, who stand down. Soundwave tells Starscream Nergill's message was scrambled. Starscream tells him to unscramble it, as he doesn't trust Nergill. Nergill tells Megatron perhaps they can be allies, and leads the Decepticons into his city. He tells Megatron he's told his guards not to harm the Decepticons.

Nergill shows Megatron how he and his people operate. Their city is abound with energy, but to use it they must remain beneath the sea. It doesn't take long for the Decepticons to set things up to start creating energon cubes. Megatron tells Nergill he will no longer have to be imprisoned in these depths, as thanks to Decepticon technology and energon cubes, Sub-Atlantica will rise from its watery isolation.

At the Autobot HQ, Spike, Bumblebee, Wheeljack and Hound take on the Dinobots... in a game of football. Spike passes to Hound, and he thinks he's heading to touchdown city, only for Slag to "tackle" him by charging forward. Wheeljack then stops the game as Optimus Prime wants them on the double.

Prime tells them they've picked up a mysterious energy flare from the deepest part of the Atlantic. He wants volunteers to check it out. Hound, Bumblebee, Wheeljack, Brawn and Spike put themselves forward, and leave the Autobot HQ. They drive into the sea and dive down.

Spike leaves Bumblebee and the group head down, where they come across Sub-Atlantica. Spike says there are legends of a sunken city known as Atlantis, but he never believed them until now. Before they can do any more investigating, some Sub-Atlanticans appear and start shooting at the group.

And to make things worse, several Decepticons arrive and join in. Spike says they need to get out of here and report back to Prime, but Wheeljack gets cut off. He tells the others he'll hold them off whilst they get out. Brawn takes down Starscream and tells Wheeljack to follow them as he and the others head into a cave.

But Wheeljack shoots a missile at the cave's entrance, blocking it off with debris. Megatron tells Wheeljack he has been foolishly gallant, as his selfless action will cost him his function cycle. However Nergill asks Megatron if he can take him prisoner, to which he agrees.

Nergill uses a scrambled telepathic message again to his troops. Megatron asks what he just said, and Nergill explains he just told his forces to watch the prisoner, nothing more. Starscream doesn't think that's the case, and has Soundwave play the instruction back unscrambled -and they find out Nergill just told his troops to take the Autobot to his laboratory -they'll use him to develop weapons against his comrades... and against the Decepticons.

Nergill returns to his city and orders for the hydro-thrusters to be fired. They are activated, and the city of Sub-Atlantica rises out of the sea. The retreating Autobots get blasted at, but are able to escape to dry land.

Bumblebee says they need to contact Prime right away, as he uses a device to figure out where Sub-Atlantica is going: Washington D.C.! Megatron tells the Decepticons this is their first step in their conquest of the world, and leads his forces towards the city. But Starscream stays behind to spy on Nergill, and watches as the King walks off, talking about how once the Decepticons have helped them conquer the humans, he shall conquer them.

Prime and several Autobots head to Washington, where they reunite with Bumblebee and the others. Prime sends Bumblebee and Spike on a mission to free Wheeljack, whilst they will take on the Sub-Atlanticans and the Decepticons. Meanwhile, the Sub-Atlanticans arrive in Washington and begin their attack...

...as do the Decepticons. They quickly take over the city and place a generator inside it, which creates a "dome of invulnerability". Before it is completed, Prime's group are able to pass it, and enter Washington.

Megatron declares the city is his, just as the Autobots show up. An explosive battle begins, as Hound tells everyone to watch their aim -they don't want to blow away any history! Meanwhile, Bumblebee and Spike go back into the sea, but they see that Sub-Atlantica is also protected by a dome of invulnerability.

Bumblebee suggests that if they can't get through it, they'll just have to go under it, so they dive down and head inside from below. Wheeljack has been hit by a disabling blast, which Nergill has used. Nergill is pleased that his magnetic dysfunction ray works perfectly.

Starscream appears and tells him to hand the weapon over -he has a better use for it. Nergill responds by blasting him, leaving Starscream immobilized. Starscream tells the traitor he shall pay, but Nergill just laughs. It seems his weapon isn't quite as effective against Decepticons as it it Autobots, but it will do. He then leaves the room.

Starscream manages to drag himself over to Wheeljack, and connects a wire to him to try and drain his power. Bumblebee and Spike then appear, and Bumblebee tells him to stop, as what he's doing could ruin Wheeljack's function circuitry. Starscream says so what -ruining Autobots is his life! He manages to charge, but in his weakened state, is easily dealt with when Bumblebee charges into him.

Bumblebee can't quite believe what he's just done, but Spike asks him to help fix Wheeljack. They do it, and Wheeljack says they've got to hurry -they must stop Nergill before it's too late!

Nergill arrives in Washington and creates an opening in the dome shield, unaware that Spike and the others are following him. At the battle, Brawn attaches a cable to Thundercracker, allowing Prime to easily shoot him down.

Nergill appears and tells Thundercracker not to worry -anything a Decepticon can start, he can finish. Using his magnetic dysfunction ray, he quickly disables several Autobots, including Prime. Megatron says the pompous Sub-Atlantican may be good for something after all.

Wheeljack, Bumblebee and Spike arrive and see what Nergill has done. Wheeljack decides to contact HQ, and says he needs the Dinobots to help. He explains what has happened, and Grimlock says the Autobots have bitten off more than they can chew... then they send for them. But he tells the other Dinobots they will go.

One of Nergill's Captains complains that they shouldn't have to tolerate the overbearing Decepticons, but Nergill tells him they will soon give them their just deserts. Meanwhile Megatron vandalizes the Lincoln Memorial so he can make a new throne for himself -he thinks this throne was made for him!

Thundercracker goes up to him and asks why they must share their power with the obnoxious Sub-Atlanticans. Megatron tells him to be patient, as they will soon put them in their proper place -the bottom of the sea. Nearby, the Dinobots arrive and work together to shatter part of the dome shield. Grimlock finds Prime and tells him he's here again -to pull his diodes out of laser fire.

Megatron tells him to concentrate on saving himself, and starts firing at him. Grimlock transforms and gets into a fight with the Decepticon leader, as Nergill and some of his troops run up. One of his soldier tells him to fire, but he says he doesn't have a clear shot. But he then decides to zap them both.

Before he can pull the trigger, Starscream shoves him from behind and yells to Megatron that Nergill is now their enemy. He takes Nergill's magnetic dysfunction ray, but before he can use it, Wheeljack and Bumblebee attack him, causing him to drop it. Grimlock catches it and snaps it, blowing it up.

The immobilized Autobots are freed, and Megatron tells Starscream to look at what he's done. The Sub-Atlanticans retreat back to their city.

The Decepticons decide to follow them but before they go, Megatron says he'll leave a souvenir. He punches the Washington Monument, causing it to break into two pieces. Prime runs up to stop it from falling, and with a little help from Grimlock, saves it just in time. They put it back in place and Slag seals the two pieces back together. With that out of the way, Prime tells everyone they'll pull the plug on Sub-Atlantica once and for all.

At Sub-Atlantica, Megatron demands for Nergill to answer to Starscream's claims of treachery. Nergill says it'll have to wait, as the Autobots are attacking. As the Autobots open fire on the city, Prime drops off the Dinobots and tells them it's time to act prehistoric.

The Dinobots transform and start wrecking the place, and Nergill sees his city is being demolished. But he decides he'll use their energy stockpiles to blow Sub-Atlantica, and everyone on it, to nothingness! He starts to descend, but is seen and followed by Wheeljack, Spike and Bumblebee.

They see Nergill heading towards a pit, but he warns them that once he throws this switch, they'll be nothing left to see. As this is going on, Rumble and Ravage appear, having heard everything, Rumble says Starscream was right -Nergill is crazy!

And if he wants to blow himself up, he'll have to do it somewhere else. Rumble use his piledriver arms to shake the room up, causing Nergill to fall. Nergill gets back up and heads back to the pit, but is followed by Wheeljack.

Wheeljack gets to Nergill too late, as the King drops the switch below, which causes a large explosion. Bumblebee contacts Optimus and tells him what's going on, as the whole city begins to shake. Prime tells the Autobots to evacuate at once.

Megatron realizes something's wrong, and tells the Decepticons to move out. Prime heads back in to find Wheeljack and the others, but is surprised to find Grimlock. Grimlock thinks he's joking, as who is it who always saves Autobot hides? They work together and quickly find the others, and then head back out.

They swim out and watch as Sub-Atlantica sinks, but Spike realizes that they've lost Nergill. Prime tells him not to fear -he doesn't think they'll be hearing from him for a long time. Spike wishes they could say the same thing about the Decepticons.

NOTES

-The scrambled telepathic communications Nergill uses twice in this episode can be properly listened to if slowed down:

The second one is a bit weird, because when Soundwave plays it back, he gets a completely different message from it!

-This episode's animation is really great, one of Toei's better episodes. However it's unfortunately remembered for a rather glaring error:

Prime and Prowl watch in horror as the Washington Monument is about to fall, but two shots later, Prime runs towards it... as another Prime continues to watch!