Return to the Underground

"Return to the Underground" is the thirty-ninth episode of the animated series Teenage Mutant Ninja Turtles (2003), which originally aired on March 6, 2004.

Information
Major Characters:
 * Donatello (Sam Regal)
 * Leonardo (Michael Sinterniklaas)
 * Michelangelo (Wayne Grayson)
 * Raphael (Frank Frankson)
 * Splinter (Darren Dunstan)


 * Secondary Characters:
 * Quarry (Dan Green) / Sydney (human counterpart) (Megan Hollingshead)
 * Stonebiter / human counterpart
 * Razorfist / human counterpart
 * Spider monster / human counterpart
 * Ram horn monster / human counterpart
 * Insectoid dragon monster / human counterpart
 * Scorpion tail monster / human counterpart

Main Locations, Vehicles and Accessories:
 * Underground city
 * Turtle Tunneler
 * Turtle Tech-packs

Voice-Over Introduction
 Donatello : A while back, I made a promise to some friends... and, believe it or not, that thing struggling in the net right now is one of those friends. You see, it's kind of a long story. Our friends were mutated into monsters by the Shredder's scientists; now, they're forced to live underground, prisoners of an ancient city powered by a giant crystal moon. And I believe it's these very same special crystals that are the key to saving our friends, and hopefully curing them for good. Trouble is, right now, my friends don't particularly want to be cured.

Plot Synopsis
Donatello is busy studying the crystals, which he thinks is the key to saving their mutated friends in the underground city. He works for a long time while the others played and trained. When he fell asleep, Don dreamed that Quarry was telling him to hear the crystal. Upon waking up, Don realized the answer. Waking up his brothers, he demonstrated that only highly concentrated sound can liquefy the crystals. With it, he made the perfect cure. To get back underground, Don unveiled his latest creation, the Tunneler, a subterranean vehicle armed with an energy drill that can reduce the time getting back to the city.

Upon arriving, the Turtles discovered that the Crystal Moon was gone and were attack by their mutated friends, who tossed them into the lava. Thankfully, the Tunneler was equip with heat shields, which protected them from the molten lava. Going deeper into the city and leaving the Tunneler and armed with Tech Pack, the Turtles discover the last survivor of the city, might not have been the last. Suddenly, Quarry attacked but was injected with the serum Don created, turning her back to normal. After learning Quarry's real name was Sydney, the Turtles found out that the humans used up a lot of crystals, so they tried to get a bigger piece out of the Crystal Moon. Using geos they found lying around, they accidentally loosened the crystal, forcing it to plunge into the lava. Without it, everyone turned back into monsters, attacking each other and anything that moved.

The Turtles devised a plan to bring the crystal back up, since even something that size can only be liquefied by sound. Sydney went with Don in the Tunneler to find th crystals while the others were up top, fighting everyone else. The plan was a success, and everyone returned to the surface.

Quotes
Michelangelo: Nets! I'm all out of nuts! ...I mean... Nuts! I'm all out of nets!

Miscellanea

 * Second appearance of the Underground, Quarry, Stonebiter and Razorfist.
 * Quarry's real names is revealed to be Sydney. In "Notes from the Underground", they asked Quarry if he could remember, but all he could say was the S sound.
 * Similar to the scene in "Notes from the Underground" Quarry is changed back into an attractive human girl, but due to having previously been in monster form she is naked so the camera only shows her from the shoulders up. When the other monsters are changed back into people, they too are naked and only viewed from the shoulders up.