Following the alignment of the planets of the Solar System, strange tremors and weather start to rock the world. The Turtles are led back underground in their investigations, only to find the underground city once again booming with life. But the people of the underground city are not friendly, and their actions could spell disaster for millions of humans.
This episode provides examples of
- Atlantis: Or Y'lyntis, as it's called here. The Turtles comment on this.
- Beneath the Earth: The Y'lyntian colony
- Bittersweet Ending: Versallia's aid to the Turtles has saved the world, but at the cost of destroying what's left of her civilization. However, Versallia has heard rumors of other Y'lyntians managing to escape the city and intends to find them.
- Call-Back: The green men were originally humans mutated by the Y'lyntians.
- Convection, Schmonvection
- Drives Like Crazy: Mikey's an even worse driver than Donnie used to be.
- Flashback: Versallia shows the Turtles a recording of the rise and fall of Y'lyntis.
- Foreshadowing: The other two mutated forms shown in the flashback are Merpeople and Avians.
- Genre Savvy: Mikey doesn't know why they keep returning to Y'lyntis, considering how badly it goes for them each time.
- Magma Man: The Lava Wraiths
- Power Glows: The Crystals, in particular the Crystal Moon. Also the Y'lyntians' energy beams.
- Pluto Is Expendable: Mikey eats it, thereby demoting it.
- Shout-Out: Versallia tells the Turtles: "Come with me if you want to live"
- The Smurfette Principle: Versallia seems to be the only female Y'lyntian of note.
- We Need a Distraction: The three Turtles distract the evil Y'lynthians long enough for Leonardo to foil their plan.
- When the Planets Align: What helps recharge the Crystals.
